Chevy86 IROC-Z

iTrader: (17)

Damb.

Chevy86 IROC-Z

iTrader: (17)

Did everyone hear the FP whine in the video that I provided?

ZZ3Astro

My fuel pressure gauge results are in... Holy Cow!! I have NO pressure from the get go. I see 39 PSI during the prime. Once it starts up and idles (I have about
14 inches of vacuum at idle), it should show about 32 psi based on the prime pressure minus idle vacuum. I have 17-24 psi at idle. It does spike to about 30 momentarily and randomly but instantly falls back. Even when cold, I accelerated at 13 psi boost and the highest fuel pressure recorded was a priming pulse of 37 psi! This means I only have 25 psi of fuel pressure relative to boost. When the coolant was really hot, that dropped to less than 10 psi relative and it leaned out of course.

Got some video of this as well http://www.youtube.com/watch?v=ydiC2...ailpage#t=264s

panhead201

So what do you think it is?backpressure from the tank?lousy pumps,fuel blend?it's like being back to square one.panhead201 You think it's just a viscosity issue,cause I don;t know about you,but I've got no idea what's in this blended gas anymore.

Chevy86 IROC-Z

iTrader: (17)

Looks like this thread has died off pretty quick.

ZZ3Astro

Update on mine.. I started it up and pinched off the return line. Fuel pressure shot up to 70+ instantly. Seeing this, I decided to swap back to my original regulator to see what it would do. Results were the same, except about 2-3 psi more across the board. Same drop in pressure as boost comes up. My filter is fairly new, but it might be work a shot to replace it next. First though, I'm going to pinch the return line with two pieces of wood and some vicegrips such that I maintain 60+ psi. I'll leave the regulator unplugged. Then I'll make a new tune to get it driveable and see how the fuel pressure does as I go into boost. If pressure falls off, I'll know it is a fuel volume issue which will be either tank/pump/lines or filter related.

panhead201

Do you think the stock pump will ever cut it with the megasquirt and turbo?panheas201

TTOP350

iTrader: (8)

my guess? nope.

panhead201

yeah,me too.panhead201

ZZ3Astro

Stock pump was good to about 9 psi (non intercooled) with the turbo on the stock engine. Then I had to go to a Walbro 255.

panhead201

OK,now I got it.I was going to go to the same walbro,now I guess I'll reconsider that.Thanks,panhead201

panhead201

Did you measure your fuel pressure on both sides of your filter?

ZZ3Astro

It should be able to support my current and planned power levels. Shouldn't be a problem up to 500-550 rwhp.

No haven't gotten to that point yet. No easy way besides running a T off the short rubber lines that come off the tank. It's not gonna be a filter restriction with that Wix filter though. Next thing I'm going to do is run a temporary power wire directly from the pump to the battery to see if there is any change.

panhead201

Yeah,I know exactly what you're talking about.I was laying under mine today trying to bypass the primer circuit so I could get my pump to run and I could get the 15 gallons of low grade junk i've got in it now so I can drop the tank and start figuring out what size fuel cell Ican fit in it.The bigger the better for what I'm wanting to do.I'mtrying to get about 36 gallons in it.So I figure I'll cut out the boot and msake an upside down L shaped cell.There's only 499 people in this town but McAmis racing is here and bickel race cars is here and bare knuckle choppers is here too.I guess there's something in the water,All of my friends either own the place or work there.McAmis builds top fuel cars but they make most of their money selling parts at the races and shows.Anyway,I'mprobably drop the straps but I'd rather do it on an empty tank.If you get it figured out please let me know cause I'm gonna need quite a bit of pressure.All Whipple will me is that I need between 12 and 13 9n the return line.good luck and I hope it works.Keep me posted. thanks,panhead201

ZZ3Astro

I'm beginning to think I might also be running into the limitations of the stock TPI fuel rail feed. They have that restrictor where the steel line feeds in, around 1/8" diameter. I'm going to modify the rubber section of the feed line with a T fitting with a flare to connect the fuel pressure gauge to. This will allow me to check the pressure ahead of the fuel rails.

If it's higher here than in the rails, I'll know its the restriction. The fix would be to then connect a braided fuel line from this new T fitting to a fitting installed in the 9th injector feed at the back of the driver side rail. Combining the stock front feed and this new one in back would eliminate all possibility of a flow restriction.

If it's the same lower pressure on the other hand, I'll know the tank/pump needs to be looked at.

Also tonight I confirmed the voltage at the connector for the tank is over 13 volts at full boost, so I'm not losing voltage from pump current draw.

panhead201

definitely not a voltage issue.Gotta be a rstrictionsomewhere.fuel line ID? 3/8ths I think.7/16,1/2 inch hardline to1/2an line to rail?Return line restrictor?I've gotta use a vacuum controlled one on the tbi supercharger.Foreign territory for me.Thats why I'm thinking about aPredator slide injector,blow thru,angle should'nt bother it....0 to 800 cfm,one moving part.thats why I'm looking for a tbi to 1405 flange.

ZZ3Astro

Well I can now confirm, in my case at least, that the rail restrictor is not playing a role. I'm down to pulling the tank and either replacing the Walbro 255 or finding a split line feeding off of it.

panhead201

Is it possible your pickup tube is cracked?Does it do it at all tank levels?I spoke to somebody at gm today and e85 blends were destroying
pump impellers in weeks.The way he was talking it sounded like recall/retrofit territory.I was really busy when he stopped by so we did'nt have a chance to go into detail.I spoke to a walbro rep at the track one time,nothing to do with this,we were running two dominators on a 12-71,ended up with two pumps,one to each carb,1 inch fuel lines,and the guy was really helpful and well informd.Maybe you could call thier tech line and see if it's becoming an Issue.We were running a BIG dry block and they were taking forever to stage us and it got pretty warm so I dont think heat is a problem.panhead201If I was gonna replace the pump I think I'd recirculate some pump gas through it for a while then do it again with a heavy blend.Take temp,pressure readings on both.

ZZ3Astro

Yep at all tank levels. I was thinking either a problem with the pickup sock or a split hose between the pump and the metal lines.

I pulled the tank tonight and I may have found the smoking gun! It was not at all what I had suspected to be the cause, IF the problem is resolved when I test it tomorrow. I'm also quite certain this is going to be the cause of most of the issues in this thread IF it solves my problem.

It all has to do with the fuel return line. The fuel pump is actually mounted to the return line tube. This tube dumps directly at the bottom of the pump, about 1.25" for the centerline of the pump inlet. Depending on the orientation of the sock, it dumps the return fuel either right next to the sock or in my case DIRECTLY INTO the top of the sock. There was a tell-tale dark circle on top of the sock that I was trying to figure out the cause of. I had already taken it off, so I stuck it on and rotated it around. It lined up exactly with the return line! This means that not only was the 150+ degree fuel rail heated fuel dumping into the tank, it was going directly back into the sock where the impeller was very likely cavitating between the heated fuel and the vacuum, not to mention the turbulence and possible boiling fuel coming down that line.

My "solution" to this "problem" was to cut a piece of 22 gauge sheet metal about 1" X 2". I bent it into an L shape, cut slots as needed to fit it between the sock and the return line and tacked it in place with my tig. Now the hot return line fuel is diverted away from the sock. This should create a slight flow of fuel from the opposite side of the sock, across the sock and then mix with the return fuel. By the time it gets to the sock it will have cooled.

I put those terms in quotes because all of this is in theory at the moment. I'm running out of options. The current pump looked perfect and not a speck of anything in the pickup screen. I'm 99% certain the pump was fine, but I also replaced it since it is a pain to get to.

Now there is a problem with this theory. If the fuel pressure was dropping to 20 psi, it seems the regulator would have been completely closed. With that being the case, no hot return fuel would have been going directly into the sock, and the pump should have regained its prime and delivered full supply. Excess fuel would once again be returned into the sock and the process would start all over again. This could theoretically cycle very quickly and my electronic pressure gauge might not be able to register the quick spikes, or my whole idea could be hogwash.

In any case, I don't want the hottest fuel on hand sent right back to the fuel rails, so this fix can't hurt anything.

I'll keep you guys posted.

ZZ3Astro

This is not my fuel pump pic but you can see the return line pretty good here. The fuel pump brackets are welded to it. The sock in this pic is a stock one but the Walbro is wider, so it is closer to the pickup even if turned sideways as this one is. Mine was oriented with the sock directly under and parallel to the fuel level float.

Chevy86 IROC-Z

iTrader: (17)

ZZ3Astro, Your determination has gotten my attention to the fullest. I'm very eager to find out your results. I noticed that you have an 87 IROC. Click on the 1987 in my signature block. It may benefit you in the future.

camarosrock1989

iTrader: (1)

Well drove the car for about a hour yesterday, Stopped at a friends turn the car off and I could hear the gas boiling bad! Waited 30 min tried starting, whine and no start. I had to wait for 2 hrs for the gas to cool before going home. Sucks.. A mechanic said he thinks its my exhaust to close to gas tank. I live in Az this is getting old, i have a few things going to change out and if doesn't fix the problem. I might just sell the damn car. I love to cruise but hate to stop for gas to cool. I sure hope one of us finds a solution.

Chevy86 IROC-Z

iTrader: (17)

WOW!!!!. Im not far from you, just 50 miles west of Yuma. I take my IROC out but I never get or hear any boiling sounds from my tank. Something is definetily wrong. Does your camaro have the exhaust heat shield in between the mufler and tank?

camarosrock1989

iTrader: (1)

Yes Chevey86 I have all the heat shields in place. The car runs great! Funny thing is its only been happening for about the last 2 months. Is yours still having this problem?
I know a lot of the guys on here are. Funny none of us can get to the bottom of it. I have talked to some good mechanics and they just shake their heads, like never heard that before. So I was thinking about re-doing my whole exhaust and see if that would help.

Chevy86 IROC-Z

iTrader: (17)

Yeah man. Mine has no issues at all. It doesnt stall, no boiling, no nothing. I do get high pressure but only when my fuel level is low. My CHIEF complaint about the fuel pump whine can be heard in here ( https://www.thirdgen.org/forums/post...7-post188.html ) . All I have is just the wierd noise.

ZZ3Astro

Results are in! When I said "tomorrow", I didn't think it was going to be at 12:15am

I just couldn't take the anxiety of knowing I would have all that work (putting fuel tank back in and all supporting work involved) so I just pressed on and finished it all up.

I've got fuel pressure!! I spent most of the test drive pulling tons of fuel out to get the mixture above 10.0. Finally got it around 10.7 and thought I'd throw some timing into it since I haven't been able to do much tuning with all of the issues. I'm only running 23 degrees of timing at 13 psi at 5000 rpm and it looks like I can go to 28ish with these heads. So I added 1.5 degrees and that was enough to lean it to 10.9-11.0. I won't use the word rocket ship because thus far I haven't been happy with the engine, but it is running like never before. Feeling like there is a chance I'll make it from here finally.

So did the new pump fix this or the effort to get the return fuel further from the sock do it? I'd be pretty surprised if the pump was the problem. It's not a year old yet, had no problem until high fuel demand and hot fuel rails increased the problem. If I can get that pump in another car I'll be sure to update this thread. For any of you experiencing these problems with a Walbro, I'd definitely look at the proximity of the return line to the sock.

Chevy86 IROC-Z

iTrader: (17)

I just think that this issue is not as important at all. Everyone is stuck with "Fuel too hot" and and too much pressure. But when I post up the link to my FP noise, nothing. I asked the board about their opinions and I get no reply. Its like everyone is so concerned about their own problem. I mean this message board is to help everyone out right? But as far as I can see, everyones issue is their own issue. So with that said, I think everyone should PM their phone number and talk over a LAN Line. I mean if 1 guy ONLY communicates with 1 other guy, well then call each other and leave the board for those who are willing to help each other out. An example would be in my case. I posted a link so that I can get some feedback about my issue and I didn't get squat. Even some of the moderators dont help. The moderators (in other threads) are supposedly the most knowledgeable. But when you PM them for help, they dont reply. pffft.

Chevy86 IROC-Z

iTrader: (17)

wow. So the heatshields are in. HHMMM. Well that is a tough one. Do you have any AM headers? since you have the heat shields, that takes care of the muffler being too close. With that said, the fuel being returned to the tank is extremely hot. By any chance, do you have a lazer thermometer? Try to get your hands on one and shoot the fuel return line at various points. You wanna pinpoint where the return line is getting severly hot.

camarosrock1989

iTrader: (1)

Chevy86 I hear ya, a guy I know has the same problem as you, fuel pump noise.
I wish I could help you, I just don't know enough about these cars as most guys do. And i do some of my own work but being a girl not strong enough for most of it.
Are there many guys around where you live that have third gen cars? I have about 5 guys in the area and believe me they are all consumed with working on there cars also,
or just busy working jobs. Life in the rat race..lol
I hope you figure it out

Chevy86 IROC-Z

iTrader: (17)

WHAT!!!!! Your a girl!!!! Damn1 No offense. I thought you where or the other gender. Wow. A woman with a 3rd gen muscle car.. Yup. Im actually in a small car club called Imperial Valley Muscle Car Club. Theres a about 9 of us but the only 3 of us are committed. Here is a link of us having a meeting.
1. http://www.youtube.com/watch?v=C02YmfexbmQ
2. http://www.youtube.com/watch?v=QIC4UetBZUw
3. http://www.youtube.com/watch?v=xNnP5GciCk8 (me spinning the tires)

panhead201

i like the cavitation idea,especially with overheated fuel.The fuel may be boiling,generating vapor.If youve been in an outboard boat and the prop cavitates,you don't go anywhere.It's cavitation.Lack of water for the prop to grab.Cavitating is actually boiling.The normal boiling temp of water does'nt apply.(212,whatever)The eater will boil at 50-60 degrees.The excitation of the molecules to a certain speed is what creates it.So your intake tube would be pulling in a great deal of vapor,not enough liquid.Definitely a pressure drop,fuel loss.Cool theory,sounds like it's got potential.My first serious girlfriend had a gen 1 formula 400.White W/blue stripes.I had a 67 vette,427-435,l88 factory tanker.M22,aluminum heads,solids,it was a track car.Every friday or sat. we'd have street drags in the summer.About once a month she and I would race.I'd always let her beat me.She actually did once,I missed a gear.My friends would do the same thing,edge her out every now and then.She bought it new and built it herself,for the most part.She still has the car!We kept her off the track with the out of town wise guys.A lifetime of great memories,thanks for reminding me.The rat race is over,the rats won.I think maybe you got it this time.Anybody ever tell you that you were persistent?Keep up the good work,you've made me have to think.panhead201

ZZ3Astro

Ok, second day of testing has begun. This morning we took it to breakfast and abused it tons. No fuel delivery issues, no changes in AFR even as the engine reached 220 degrees.

Here is some video of what I'm talking about and what I did to keep the return fuel away from the sock. http://www.youtube.com/watch?v=RKKUE...ailpage#t=330s (there is more to the video but this links to the important part)

Someone mentioned the LS1 tank design having the fuel return going into the bucket with the pump/sock. I believe at least some of the LS1 cars have an in-tank regulator, so the return fuel goes no further than the filter before coming back to the tank. A big part of the problem for our cars (in theory) is the heated fuel from the rails getting back into sock (esp the wider Walbro sock). Also I'm thinking the returned fuel on the LS1 tank is further away from the sock than our cars. In my case is was dumping directly into the sock.

ZZ3Astro

It's true, I have been focused on my specific issue but I did hear the sound on your video. It's pretty difficult to compare to the sound mine makes, but I can tell you when mine was acting up, the fuel pump would make a stuttering sound at idle. It would come and go about once per second, from normal to stuttering and back to normal. Now that I think about it, having realized my issues likely were from the return line, the stuttering sound is exactly like a boat propeller ventilating while on plane. Also similar to tire slip at 70 mph in a 700 hp turbo car! Kind of a grab-slip-grab-slip-grab-slip thing.

In abscense of a better way to do it, this is the written version:


whiiiirrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr-wh-whi-wh-whi-wh-whi-wh-wiiiiiiiiiiiiiirrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr-wh-whi-wh-whi-wh-whi-wh-whiiiiiiiiirrrrrrrrrrrrrrrrrrrr

LOL

panhead201

Cool,man.I think you got it figured out. my audio is'nt working on my computer,I think I had less r,s but I think you did it.I like the deflector idea I saw in the vid,Of course the temp is gonna elevate after a slow ride through the fuel rails and the return lines being bolted to the intake.Pretty smart.panhead201

Chevy86 IROC-Z

iTrader: (17)

panhead201, your sound is still bad? damb.

T/Atime

great idea! i guess will see how it works out over time. makes me wonder which way my sock is installed... i think right in the path of my return. i might pull my pump now to prevent premature failure with my new pump

panhead201

Stock pump,yeah,but now that zz3astro seems to have figured it out,I'm going with an external walbro,large approved fuel cell because of supercharger.Thinking about dry sump crankcase,rear oil sump with inline coolers along frame rails.trying to move weight to rear,balance car.Decided not gonna race til spring unless Iget a couple of sponsors.Trying to lose about 800lbs off this car.Thats a lotta cutting and chopping off this car plus aluminum block.But I've got all winter,unless I go to Fla or Cali,or win the lottery.There ain't gonna be much T/A left by the time I get done.This is my first pontiac,except for a 63 bonnie a long time ago.I'm having a blast with it.These threqads have been helpful,especially this one.Thanks guys and lady for all the info.panhead201

panhead201

I see your point on this particular issue,but a couple of us,including you,kept at it and everybody contributed a bunch of different ideas,opinions and I think we all figured it out.Without the help of the zen masters.Like the audio you posted,it takes a while to digest it,consider causes,possibilities,etc.This is the first website,forum,whatever you call it,I've ever joined and I've learned alot.You filter out the bs and bad attitudes and there's a lot of info to be gained.Anyway,Thanks panhead201

Chevy86 IROC-Z

iTrader: (17)

. There is a lot of that B-essing. There is a ton of good stuff. The issue is finding out what is the junk, and what is good solid info.

panhead201

actly.Like in the case of what you posted,it eliminated voltage fluctuations as a possible cause.To my way of thinking finding out what it is'nt is a major part of what it isThe variation of fuel supply caused your readings.Empty pump will run faster than a full one.I thought it was good work and helpful to me,anyway.Later,panhead201

ZZ3Astro

Ok, follow up report time.. Tonight I saw 52 PSI of fuel pressure! No more fueling problems at all. Now if one of you wants to come drop my tank for me, I'll be glad to put the other pump back in LOL. We'll test it out soon enough and I'll try to remember to put the final results in this thread. Or, someone else can 'fix' theirs and see if the results are the same as mine.

Orr89RocZ

iTrader: (20)

Fuel pumps arent suppose to whine excessively so there is a problem with the pump or fuel becoming too hot around the pump, causing problems when its trying to suck in fuel and pump to the rails.

I"ve mentioned it before, I thought it was a pump problem that these people were seeing. I havent had these issues on any of my walbro pumps. ZZ3 appears to have fixed his problem with a new pump.

I'd like to think that there may have been a bad batch of pumps made at some point in time, or possibly you bought a knockoff walbro clone pump that isnt of the same quality. Hard to say.

ZZ3Astro

Orr you may be right about it being the pump, but both of mine came from the same source -> Precision Turbo.

I'm pretty confident that the old pump was fine though. Looks like I need to make up a test jig with a bucket and video camera to prove my theory. It would transfer fuel from one bucket to another while maintaining a head pressure of ~40 psi. The flow through the diverter valve (simulated regulator) will then spray back into the source bucket. The test would involve changing the position of the return line relative to the sock. If my theory is right, when the return line gets too close to the sock, the pressure should drop off.

Orr89RocZ

iTrader: (20)

That would be a nice test, but also if you can throw in the element of heat to see what effects that has on pressure/flow.

OR you can drop the tank again....

ZZ3Astro

LOL... ORR can drop the tank lmao. I know heat is a factor, but I think it only plays in below a certain flow level. In other words, the problem is worsened by heat and affects lower flow requirements as the heat increases.. Or at a certain point, the fuel starts boiling in the rails and affects ALL flow requirements. In my case, the new engine needs more fuel at the same boost level than before. Ah, theories. Well if I get time I will do this flow test.

TTOP350

iTrader: (8)

I also believe its a weak pump problem. Bad batch? or cheap aftermarket pumps failing.
I have replaced many pumps that had pressure but no volume. cars would run fine until they heated up or the car was run hard then they would peter out.
I was always told that the fuel return line was positioned over the FPsock to help keep the fuel pump primed under low fuel level cornering. right or wrong? Who knows?
The cars didnt have this problem when new. Buuut they didnt have headers and Ypipe mods like cars do now.
I'm still convinced its a fuel pump/split in tank rubber line problem in most cases..

-srs-

So for us guys guys that are shadetree mechanics, what do you suggest we do to solve this return line/sock problem?

RBob

iTrader: (1)

You are correct. Walbro produced a boat-load of 255 lph GM style pumps that were bad. Over time they lost pressure. Some worse then others.

The part number of the pumps ended with 0169.

I'll find the thread on the Turbo Buick board and post a link. These are the folks that were losing engines due to this, and pushed Walbro into a corner.

RBob.

RBob

iTrader: (1)

Here are some links. First is about the issue starting to happen.

Second link is Walbros' response.

http://www.turbobuick.com/forums/gen...o-failure.html
http://www.turbobuick.com/forums/gen...mp-update.html

RBob.

Chevy86 IROC-Z

iTrader: (17)

Thats why RBob is a moderator. He has the knowledge. If he doesnt know, he will find it and let everyone know his results. He gets info when most needed. A++++++ to RBob.