At a loss:

I posted this on a facebook group too, but just getting some extra eyes incase others have ran into this experience:

its a 5.3 in a 1987 Trans am formerly a TPI car. Not fully tuned but drives.

Fuel pump went out Replaced with a eBay cheapy. First mistake. Months later went dead and replaced with a genuine GM acDelco. Even got the Typhoon / Syclone pump. Car won’t start. Getting 10-13 psi at fuel rail. Changed fuel filter. Still 10-13 psi at fuel rail. Car still won’t start. I’m using the stock fuel lines too. I found the old sock fell off and the plastic color fell part. Could the lines be clogged? How could anything get past the fuel filter though...

Could the corvette fuel pressure be bad? How often do they go bad? Car has been sitting off and on and literally has like 20 miles on it maybe over the last year.

How important would the "hot wire" be at this point? Pump is getting 12V when you first crank the key. THEN it falls since it only "primes" for a few seconds. I'm running fully stock "wiring".

Any insight or thoughts are appreciated.

 

What is the typhoon pump rated at? You need 58 PSI at the rail. I would replace the C5 filter just because those are cheap and easy. Are you running the return line from the C5 filter back to the tank? Meaning, you modified the stock return line? I don't know what kind of power the typhoon pumps takes but your stock wiring will be enough to run any OEM pump up to 255lph (common cheap pump people run with small displacement LS swaps).

Quick google tells me stock fuel pressure was 42-44psi on those boosted 4.3's. Assuming same GM fuel line size you likely don't have enough pump.

 

is the line that connects the pump to the sending unit damaged? Mine deteriated and fuel pressure was bleeding off back into the tank

 

I would get adapters and test the pressure right before the filter. More than likely you have a small leak inside the tank between the pump and the pump housing.

 

I'm not sure honestly. BUT I know it was a solid upgrade back in the TPI days. Supposed to still be good for LS Swaps.

Yeah, Vette Regulator is up underwood mounted on Drivers side fender. both fuel lines (sending/returning) are plumbed in.

I've driving the car around and sadly only put about 20 miles on car over last 12 months. Maybe its gummed up and needs to be swapped out.

 

I removed the "pulsator" and have a hose in its place. So it goes fuel pump, hose, hardline.

I'm worried about the OEM wiring, but yeah, it was fine before.

 

Update: Still got about 15psi at the fuel rail per another gauge. NO change.

New fuel filter
New Vette regulator
Home made Hot wire running 12ga wire directly to pump (via relay, etc).

Pump sounds great. Nice strong sound and firm click from relay. Still no change in PSI. Need to hook up gauge to line coming out of tank to ensure psi from new pump is solid.

If that is strong, then I guess hook up air compressor and flow air thru lines?? Since vette regulator is under hood, I’ll unhook back there and blow the line toward tank.

Originally the sock that was only about a year old fell apart (part of the plastic inner part) and slide off the pump. So maybe parts of the plastic go sucked in the line??

I’m almost ready to go buy 25 feet of aluminum line and run fresh lines just cause I’m tired of messing with it at this point.

 

Check pressure as close to pump as possible. If still low pump, strainer etc. If strong I would inspect the lines and make sure not pinched. Especially right as it enters engine bay. You can hit it there dropping the engine in and crimp it. Also any leaks or trapped air will kill the pressure. You could also flow test to see how many gallons per hour you get to see if lines are restrictive. Disconnect fuel rail run pump into catch can.

 

As you mentioned running new fuel line,Id still highly recommend this over running the stock stuff just due to age and improve flow and place a better fuel filter close to the tank.

Sounds like either you have clogged line since you placed the vette regulator under the hood and using the stock lines front to back still.if the sock intank broke and trash has tried to pass through..god only knows where the restriction could be. The other place id check is the fuel pump assembly.Pull the pump back out...either blow out the assembly lines or triple check the hose between the fuel pump and the assembly. Ive had those tear being just very cheap and the hose clamp rips them and the pump pressure escapes into the tank. If you get anywhere near 30psi of pressure,the car will idle.

I think your issues lies within the tank.Work your way from the source of fuel to the front and just how the system works.You know fuel isnt getting enough pressure to the front,you have stable power supply to the pump,fresh regulator/filter,new pump but its still cheap(sorry but ive gotten 2 tbi pumps from gm that were in tpi/typhoon etc high pressure boxes) Suggest a 255lph walbro regardless, and lines could be clogged/pinched.Fuel system isnt too hard to figure out in our cars when it goes wrong.

And stupid enough but it happens..people mix up feed/return lines at the vette regulator also cause pressure issues lol.
Good luck,dont give up.

 

Thank you everyone for the solid feed back. AND thanks for the encouragement. Trust me. Had this car since I was 18 and I’m now 43. No giving up just yet.

Saga continues> However….

Got another rental fuel pressure gauge. Got the gauge plumbed directly on top of the tank. Directly from the source. Literally its fuel pump > 3” hose (since I removed the pulseator), then hardline > Then gauge.

14 PSI!

I literally have the line loop-de-loop back into the fuel line of the car. 14 PSI. Buddy recommended I vise-grip the hose so I peg’ the pump so the line in a sense dead ends at the gauge. I’ll do that next just for ***** and giggles.

Honestly, I think it’s the damn fuel pump. I think these AC Delco’s are junk. I’ve been scouring the internet searching AC Delco dud fuel pumps and there’s lots of bad reviews. I guess they are / were made in Mexico and /or China now a days and are just not reliable.

1st Pump AC Delco. Lasted about a year. Most of the year car sat. Car only idled a few times while putting the swap together. Only went for short blast around the block.
2nd pump about 2 months. Another AC Delco. BUT did a lot of testing/tuning. Car had only about ¼ of a tank and I let it go dry a few times. Ok. My bad! I should know better then to let car run dry. Too far from a gas station to drive “legally”.
3rd Pump. Ebay special. Ok. My fault. It was literally a $15 china special. FML. Lesson learned. Coudnt get any PSI of the thing. Complete Junk.
4th Pump. 3rd AC Delco. Cant get more ten 14-15 PSI out of the damn thing. Its new. Ebay. AC Delco plastic wrap and everything. It seems legit.

I just ordered a Denso for a Typhoon/Syclone from Rock auto minutes ago. $60.00. Let’s see what happens next.

The saga continues.

 

Thank you everyone for the solid feed back. AND thanks for the encouragement. Trust me. Had this car since I was 18 and I’m now 43. No giving up just yet.

Saga continues> However….

Got another rental fuel pressure gauge. Got the gauge plumbed directly on top of the tank. Directly from the source. Literally its fuel pump > 3” hose (since I removed the pulseator), then hardline > Then gauge.

14 PSI!

I literally have the line loop-de-loop back into the fuel line of the car. 14 PSI. Buddy recommended I vise-grip the hose so I peg’ the pump so the line in a sense dead ends at the gauge. I’ll do that next just for ***** and giggles.

Honestly, I think it’s the damn fuel pump. I think these AC Delco’s are junk. I’ve been scouring the internet searching AC Delco dud fuel pumps and there’s lots of bad reviews. I guess they are / were made in Mexico and /or China now a days and are just not reliable.

1st Pump AC Delco. Lasted about a year. Most of the year car sat. Car only idled a few times while putting the swap together. Only went for short blast around the block.

2nd pump about 2 months. Another AC Delco. BUT did a lot of testing/tuning. Car had only about ¼ of a tank and I let it go dry a few times. Ok. My bad! I should know better then to let car run dry. Too far from a gas station to drive “legally”.

3rd Pump. Ebay special. Ok. My fault. It was literally a $15 china special. FML. Lesson learned. Coudnt get any PSI of the thing. Complete Junk.

4th Pump. 3rd AC Delco. Cant get more ten 14-15 PSI out of the damn thing. Its new. Ebay. AC Delco plastic wrap and everything. It seems legit.

I just ordered a Denso for a Typhoon/Syclone from Rock auto minutes ago. $60.00. Let’s see what happens next.

The saga continues.

 

First Id be willing to bet its a tbi pump you got if its only giving you 15psi. Second thing is for a few bucks more get a damn proper 255lhp pump and be done with the tank side of things! Ordering a syclone pump doesn't mean ***T lol. What comes in the boxes are junk. A 255 wally pump is cheap and for all the hassle your already going through with over the counter pumps...Id penny up for the peace of mind you will get 60psi and more to adequately support an LS engine. A tpi pump or slightly better oem pump is a bandaid solution and you will be switching it out in a matter of time. After dropping the tank 4 times for faulty oem crap I did an access hole. Then I dropped in a 255 and no more pump issues. The next issue I had was the original wires were so old and brittle that I killed a walbro after 1.5yr. Did a hot wire kit and replaced every wire on the tank side aswell and that made an audible difference having the pump get clean stable voltage.

The question I ask you is,what is your time worth to replace the pump you just ordered?

 

Question are you sure you are getting the TPI pump not a TBI, the TBI is rated at 13-15 psi.

Also you have to have something past the gauge for back pressure otherwise really an open loop should have alot of flow but no pressure. Think open garden hose, then putting your thumb over the end, you reduce flow but increase pressure. We tend to measure pumps in psi but it is really pressure and flow combination that makes a solid fuel system.

 

 

Are you kidding me?? I went back to my purchases and saw the pump. I searched and found that its in in fact a TBI! What a fail. That’s it! Sorry for the enormous pics above. Lemme try to fix.

How do I delete this embarrassing post? Hahah.

I swear. Ebay let me down. I guess I need to do a better job in checking part numbers? FML. So cheapy ebay special pump was probably a damn TBI. THEN I get a genuine AC Delco TBI pump. Wow.

Thanks gang. I’ll keep everyone informed when I get the new/correct pump in

 

Everyone does it at some point. When a parts store asks for the VIN letter say "F" that will give you TPI parts, "E" is TBI.

Sadly you are probably stuck with a box of pumps unless you can sell them here.

 

Again..get a walbro 255 and don't look back for a few bucks more that will support way more demand,its direct fit. A TPI pump is still not adequate enough imo.

 

Thanks for the feed back. Got the new Denso pump in. Fired right up. Wow. What a fiasco. Ugh.

Saving up for a quality Walbro next. Just need to get car running for now. I know that sounds counter productive. But its done.

Thanks again for the help. Good stuff.

 

Called it lol. Well glad its up and running. Now time to work on the other small kinks as you move along.