Becouse when you filled it up two things happened.
First when filling up your adding nice cool fuel into your tank.
Secound when you fill up, there is a vapor recovery system on gas pumps that removes said vapors.
But the problem your having is the purge valve staying open, not closing when needed to.

 

Still doesn't explain the lose of fuel pressure though.

 

I'm not sure what all you have done performance wise to your car. Ive re-read this hole post. Looking to see exactly what your problem might be..
For most every one else I suggest testing there purge valve. And take a good look at the entire Evaporative Emission control System. CHeck for cracked or bad hoses, Cannister, Electrical conection.

And yes that is a purge valve your showing. There is a simple test to see if its working. You nead a hand vacuum pump.
If you have the haynes repair manual just go to page 6-15 and 6-16 and it'll tell you how.
Just try it and see what happens. If I'm wrong I'm sorry. But I don't think I am.

 

Yes it does. IF there is a problem with your purge valve which is opperated with vacuum and so is your fuel pressure regulator then it is possible that fuel pressure will drop when this is accuring. Not to mention that when this is supposed to be happening the computer leans out the fuel to comansate for the vuel vapors that are being gurnt off.

 

If the FPR looses vacuum the pressure should go up. And the purge valve works off ported vacuum so it pulls nothing at idle.

 

Except I had the leaning issue at WOT. The computer does not have the authority to make changes in WOT.

It also doesn't explain how a car can run fine for 1hr then all the sudden stop working. Then wait another hour for the car to cool down, and all is well again.

 

As I've stated earlier ,I'm not sure all that you have done to your car. I'm sure your car is not else would you have it on the dino.
I'm not sure what is going on with your car at WOT but you computer is making changes even then. Like in timing, fuel delivery. and such , its not a constant.
As for explaing why a car runs fine for an hour then all the sudden stops working , Thats how mine started And got worse from there. Untill it happend after only 15 min running. And the hotter it was the worse it became.
I was able to figure out that when it happend just unplug the neg. cable from the batt, for 2 min the plug back up and off I could go. But untill i changed out the , Well Added a charcoal canister and purge valve that the problem went away. And I've enjoyed the car every since

 

Awesome, I'm glad you got yours figured out.

In WOT the computer is "dumb" and just pulls values from a table; it is not making changes to make the 02 sensor happy. I have tuned my WOT tables to work well. I did maybe 20 pulls. Pull 19 was leaner than the previous even though I had just richened the mixture. I thought that was weird. But I richened the mixture again and pull 20 was even leaner. Weird. After pull 20 was complete, the car idled like crap and shut off. This is when I put the gauge on it and found that I wasn't getting good fuel pressure. Let it sit for 90 minutes and fuel pressure was fine again.

My car is nothing special, just your typical TPI build. Evap system is intact. Fuel lines pass about 3/4" away from the last header tube and about 1" away from the first tube on the driver side. My theory is the fuel picks up a lot of heat from the headers. Check the chart I posted earlier. The fuel entering the tank is about 15 degrees warmer than the fuel leaving the tank. The tank is slowly heating.

I still don't get how your evap system was working fine for the first hour then it fails. But maybe the valve only failed after fully heat soaked. I am not an evap expert.

 

87350Iroc, how long ago did that happen to you? Has the pump been fine since?

 

Remember that all these parts are over 20 years old. And for a piece of plastic going threw heat and cold cycles , I'm not an expert either But I just know what was my problem and what solved it. The only thing I can say from here is to check and test what ever you can. IF you have a spare purge valve throw it on and see. If it works great let others know. If not you've only wasted 5 mins of time putting it on. Its better than taking the whole fuel system apart And replacing everything like I ended up doing before I found my problem.

 

The full timeline.

Late 2008 - Walbro fuel pump installed

Mid 2010 - first failure, just driving on the road, swapped ICM and thought all was good. I don't normally go on long drives so I thought it was fixed with the ICM

Mid 2010 - second failure, on Pacific Raceway road course. Car driven very hard for 20 minutes during 3rd session.

Early 2011 - failure after 2hr highway drive

Mid 2011 - failure after 1hr mountain drive

Mid 2011 - failure after 1hr drive

Late 2011 - failure on dyno after 1hr and around 20 pulls

^^^ I may have missed one in there, hard to remember

Haven't driven car since dyno failure. I'm sure it would be fine as long as I stay under 1hr drives. I plan to use the car for Silverstate which involves a 1000 mile road trip, a 90 mile race, then 1000 miles back home. Need to get this sorted out.

 

If I remember correctly there was a bad batch of pumps in the past but having to have all your fun in a hr or less sux.
If you have logs from your dyno time, just for giggles, does it show fuel pump voltage ??? fuel pump relay contacts heating up and causing voltage probs? ground circut good?

 

Yes I have heard about the bad batch, and its right around the time I bought mine. It will be interesting to check the serial number.

I took a bunch of logs but I don't think I have any of when the failure was happening. I will take a look later.

 

theres been alot of members with fuel pumps go bad with low milage on them. im on my second walbro, hope this one lasts longer this time. i experienced all these problems listed above. its a hard one to diagnose.

evap, fuel pump voltage, replaced relay, everything checked out fine. no obstructions in my evap lines. ordered my walbro 255 (racetronix hard wire kit) car runs like a beast. one important thing worth mentioning is i set my fuel pressure with the old pump. then replaced with a new one and when i fired it up the new one was holding 52psi vs 44psi on my old one. so i adjusted my new system back down to 44psi. my old 255 was weak at best and would die after an hour.

theres a check valve built in the fp that doesnt work any more 2500kms on the new one. i emailed and called thunderracing with no response. ill have to install a new check valve external to the pump. sure wish customer service was avalible to stand by there products.
one the bright side, car still runs great with out the pulsator valve and checkvalve.

 

I Hope this helps...(its from page 6 I think)

 

My check valve hasn't worked as soon as I installed the Walbro. But I installed a replacement pulsator and I wonder if its not holding pressure instead of the pump check valve.

Like you though it still holds pressure when the car is running and the car runs well.

 

Thanks. I should have mine out tomorrow and will take a look.

 

Ok I just realized my fuel lines next to the firewall are both within a 1/4 inch of the header tube. Has anyone moved these and it solved their problem? I'm going to heat tape and maybe a tranny cooler in the return but I'm curious as to whether it fixed anyones?

 

I don't think the head tape is going to do much. You need airspace between the header and the heat shield and between the heat shield and the line. I would see if maybe you can the fuel lines away from the header a bit. I got frustrated and just decided to relocate the lines totally.

 

Pulsators are not to be used with Walbro HP pumps. The pump stem will not seal in the pulsator. The supplied rubber hose is to be used.

 

What are the benefits and downsides of the pulsator? What are the benefits and downsides if you replace the pulsator with the rubber hose?

 

No benefits with pulsator + Walbro pump, just problems. Remove it.

 

What if I wanted to rid the pulsator IF I wanted to install a fuel pump other than a Walbro?

 

Follow the pump manufacturer's recommendations.
In most cases in-tank pulsators are no longer used.

 

Hhhmm. Can somebody else give me an answer instead of a recommendation?

 

Never mind. Found it doing a search.

 

Yes I know that now. I didn't know it in '08 when I installed the pump.

Since I have your attention. Just wanted to let you know I have one of your double pumper kits that I will be installing tomorrow. And will take any tips you have.

Also, I pulled the old walbro pump out today and its date code was 17108. I think that is in the recall range. So just another piece of data.

 

The pulsator is designed to reduce noise created by the old-school FACTORY vane fuel pump. This noise is specific to the type/design of the pump.
It simply will not seal with a Walbro HP pump and it can restrict flow.
You will not use an in-tank pulsator with newer gearotor, turbine or screw pumps.
New cars put a pulsator on the fuel rail where it reduces injector noise and pressure pulsations.

Cheers

 

This reminds me of a situation in which a car was stalling after a time period and it confused many of us. Is there any chance your pump sump/filter is getting clogged with debris from the tank? The example I'm thinking of would run and drive great for over an hour, but would run lean and die due to crud clogging the fuel inlet to the pump one way or another if run longer.

 

If you purchased the DP system from Lonnie then he will provide support.
If you purchased a DP kit or G7 DP system from us support is available via our forum.

Racetronix NEVER sold the questionable F20000169 255LPH pumps with our F98 kits so we never had to deal with that 'issue'. We always bundled GSS340M pumps with our kits.

 

I bought a modified version of Buick kit from you guys. Order 108640. I tried to sign up for the forum today but never got a confirmation email. I will give you guys a call tomorrow.

Just to be clear as you say, I did not buy the 169 pump from you guys and wasn't implying that I did. Just providing information as we talked about the 169 pump issue being a possible cause a few pages ago in this thread.

 

Yahoo and Hotmail are notoriously bad for blocking forum e-mails. Our server did sent the e-mail. We just sent it again. Please check your SPAM box. We are closed for stat holiday today but techs may be around to answer questions on the forum.

 

do not use the in tank pulsator period.
throw it away and use the replacement hose suppied with the new pump.
if you do use the pulsator, your asking for trouble.

 

Currently in my tank, is the cheap Airtex FP from autozone. I don't have issues yet but I am considering a Walbro for future use. Once I do get the new FP, out with the pulsator and in with the hose.

 

How possible isit that the 10-15% ethanol that is being put in from the fuel maker is an issue?

 

good deal on tossing the pulsator with the new pump.
it took GM a few years to realize they were trouble, but they did eventually issue a TSB about them.
i dropped a few tanks more than once because of those #$%* things and started tossing them in the trash before the TSB. im certain they caused more than a few unnecessary fuel pump replacements.
also, don't use that environmentally friendly fuel hose,.. you can ask Captain Astro about that stuff.

 

I checked the IIRC, HTSB and there is nothing about a recall on the pulsator. Interesting.

 

Racetronix double pumper installed. Nice kit. I will be using the second pump as a back up to the first.

 

That looks nice and what I'm planing on doing soon. Don't forget to take that paper sticker off the wires..

 

I don't have a heat shield between the lines and the header. Just bare header and bare fuel line. The car only died 1 time prior to putting headers on and I drove it about all day. It was also a walbro pump with a pulsator. IT whined all the time. The new pump only whines after long drives. Maybe my original pump was just bad and my fuel line being so close is my problem now.

 

I've been chasing this problem foe nearly a decade. I've new injectors, regulator ,pump, and filter. Last year after the injector and filter swap I was problem free and running Shell 91 which is ethanol free. Last week I was out and about and ended up making a left hand turn with me behind the car in the usual position. My fuel pump was screaming and when I opened the gas cap it damn near left my hand. I'm thinking of having a set of pop out bobsled handles installed seeing as I spend most of my time pushing my ride. The fuel in the tank is last winters Shell 91 mixed with a bit of recent fuel of the same brand. Only difference is: There was fuel stabilizer in the tank and I also added a can of seafoam. I'm wondering if this may have affected the boiling point of the fuel? Last year it was a lot hotter and my fuel was a lot lower and I did not have the problem.

 

it wasn't a recall on the pulsator, just a TSB.
with a recall, GM would have to replace them free of charge.
since it wasn't a safety issue, they didn't have to do a recall.
the TSB says to replace the old orange pulsator with a new gray pulsator.
they used a different material in the new ones which they claim won't fail like the old ones do.
they are also easy to damage, just simply pushing it on the pump or sending unit can damage them.
myself, i don't care to take the chance by using a part that may or may not last like it should.

 

To be honest with you,I can't remember at this point.Now I,ll have to read it all back,to see.
as far as the coated headers it ain't overkill if it works.I don't know about anybody else,but everything I own has had fuel issues this year.Right down to my chainsaw.I've got a Case farm tractor that had problems after I serviced it for this season(diesel).I was'nt getting enough fuel to the injector pump,so I changed the lift pump.Did'nt help.I had to use a different fuel filter.The OEM one would'nt let enough fuel through.At five bucks a gallon this is getting a little ridiculous.Their summer blends or whatever they call it is not working out for me.I've been buying Sea-Foam by the case.It's about 9 bucks a can anymore.The paper filter in my Bobcat dissolved.I put clean gas in it and what was coming out at the carb was brown.I cut the fuel filter in half and it had literally dissolved the element.I'm seriously thinking about switching to lpg.Let me know how it works out with the headersMight be easier to wrap the fuel lines instead of the headers.panhead201

 

I carried out the EVAP test as per the GM service manual. In one of the steps you are supposed to get 10 mm hg on the Purge Solenoid with the test port grounded. I am able to get the 10 but it immediately drops off to zero as soon as I stop pumping. The electrical side is working fine. The evap purge valve beside the purge solenoid is also working fine. Do you think part of my problem may lie in the solenoid?

I did this test last year and I remember being able to maintain the 10 mm hg until I removed the ground on the test connection as per the manual. This means as a worse case scenario there would always be a vacuum when the solenoid is supposed to be closed. I figured that may no be a bad thing. Perhaps I am wrong. However how would that explain nuclear reaction taking place in my gas tank?

 

Well f*ck me I guess yesterday was hot enough to make my pump **** the bed. This is the first time since last summer, and in between then I have put a new fuel pump in and also replaced a ripped regulator diaphragm in the rail. I also aligned my fuel pump sock filter away from under the return line. I have an aftermarket cat-back exhaust and muffler, but my heat shield is in place under the tank.

All I did was drive maybe 15 minutes to the grocery store, spend 15 minutes inside, and when I came back out and turned my key I heard the pump make a very strenuous, loud whine. I started the car anyway and it immediately had idling issues and it would die if I gave it gas. The whole time I could hear the pump struggling and almost sounding like it would turn off for a second and whine back to life.

Remembering that some people here think it's a tank pressure issue, I opened my gas cap and there wasn't any irregular excess of pressure or vacuum. It also didn't help when I restarted the car.

This is clearly a fuel heat/possible quality issue and I think this thread needs to focus on that aspect. My theory is that it is a combination of the design of our TPI motors fuel systems and the change in composition of gasoline to have more ethanol. That explains why only us TPI guys are having the issue and also why people never experienced the issue back before heavily ethanol blended fuel.

 

I think I may have the tank cleaned tomorrow. I can see a bunch of debris in the plastic basin at the bottom of the tank. There was also a nice grey patch on the outside of the strainer smack in the centre of the fuel pick up. My return line is for the most part touching the strainer. However I have to agree with the theory of fuel composition. I did my mods in 1998. Thats TES headers, flowmaster muffler etc..etc. I never had this problem until couple of years. I've had other fuel issues over the past decade but nothing like this. It's not ethanol either. Shell 91 does not contain any.

 

It sounds like a fault solenoid,or relay.I'm sitting here thinkinggg about the effect it eould have.Earlier in the thread somebody mentioned a GM service bulletin about it.If GM burried it somewhere I'll be able to find out tomorrow,or Tuesday,depending on how they feel about Easter.panhead201.I've got one hell of a TPI engine on a stand and I' getting leary about putting in anything.Are you showing any codes or constant on and off serrvice engine light?

 

No codes whatsoever. I'm just trying to troubleshoot anything to do with the fuel system. At this point I have zero reliability with the car. My car was running the best it's ever ran in the 15 years I've owned it. Then out of no where, as if someone flipped a switch, the car stalled. No start after that. I lost all pressure with a rocket of fumes out the filler neck from a near full gas tank.

 

Confirmed!!!! My neighbors 92 RS (TBI) does the very same noise. He just got his motor running and it has the very same FP noise/whine. Get this, full tank, 1st start in 3 months and its a nice 88*. The second he started the RS, the pump started whining. He himself uses shell gas so there is no ethonol. So it's not just a TPI issue. It's a fuel pump issue. In my neighbors case, the temp of the gas is not an issue and there is no pressure. Obviously the pump has a problem. Perhaps a solution would be an external pump.

 

im not sure where the ideal that all shell gasoline doesn't have ethanol in it came from, but it is just a rumor.
as far as i know, all gas companies still sell gasoline with no ethanol, but depending on local laws the gas station owner must order it, other wise the gas will have ethanol.