hello

I have an 88 FB GTA 5.7 that I did a complete rebulid on 2 years ago. New pistons, rings, punched out to 355, 1.6 rollers, headers, etc. Replaced every sensor, IAC, TPS, every temp sensor, MAF etc. ALso replaced every relay , FP, maf power, burn off ,etc. running AIR pump, AGR, etc. Replaced every vacum line.

I added adjustable fuel regulator, running at 46 PSI. I am throwing no codes.

She has ran fine for 2 years

The problem. Started stalling at idel and coughing while cornering. I replaced the fuel filter and pulled the IAC. It had a black carbon, cleaned out everything and now have no idel issues, sits at about 750 RPM. But she is still gagging when I hit a corner hard, say 30 MPH it just seems like it running out of gas.

I am thinking fuel pump or something in the pick up, but the tank is fulll of gas and it still does it.

Anyone ever see this before, I have searched the forum but dont see any reference.

Thanks for any input.

 

bump ^^

 

I put in a new fuel pump relay, old one looked fine but swapped it out anyway. Still the same problem.

Now 2 days later the problems are growing, stalling out durring decelaration.

All the problems happen once she is warmed up, been running hard for 20 minutes or so.

Has anyone expirenced a fuel pump going bad that good cause this? In my past expierience ( but not with this car) they either work or dont.

 

Have you had the fuel pump out yet? It sounds as if the pickup may be partially clogged, have fallen off, or be loose/broken.

I had the same symptoms on my Ford Contour and it was a collapsed pickup "sock filter" right on the pump/pickup that was causing cavitation on hard corners (autocross).

If you can, rig up a fuel pressure gauge to watch while you're driving to see if it's a pressure related issue. Then you'll know that it's in the pump/pickup/pressure regulator line somewhere and not something electrical with a bad connection.

 

Initially I was thinking FP pickup, but you say it's the same with a full tank of gas. Then I'm thinking heat related to the ignition module, but doesn't make sense on decelleration.

If you're suspecting the fuelpump, probably best to pick up a fuel pressure gauge and tape it to the windheild or mount in the car somewhere and see if the FPsi is dropping off at the same time.

 

power brake booster leaking?
High vacuum loss when hitting the brakes when entering a turn or hard decelleration.
Maybe the check valve between the plenum and the booster.

 

I would check your plug wires and stuff too this could be an electrical problem.

 

oil level?

 

Thanks to all for the response.

oil level is fine.

I do have a presure guage, I will see if my presure drops when it starts acting up, thats a great idea.

The vac line to the brake power boost is fine. To be more specific , it is stalling when i take my foot of the gas, not necessarly when I brake. But it doesnt do it consitantly.

I have chekced the coil wires and plug wires,they look fine. It's not like its missing, it's like it is just running out of gas. All the plug wires are in looms and no heat deteration is evident.

Wouldnt an ignition mod throw a code if it was acting up?

I have not yet pulled the fuel pump to look at it and the pick ups. Depending on what the pressure test while running shows that may be where I go to next.

Thanks again for the input. I will post back after the pesure test.

 

Ok , hooked up a presure guage and taped it to the windshield with 200 mph tape. Ran the car with the vacum line hooked up to the AFPR. Presure reading never droped below 32 PSI and occasionaly would spike at around 42 psi. ( with the vacumn line disconected my average FP is 46 psi)

But it was not like a noticale drop in presure when it started acting up, coughing and stalling. So i dont think it's a fuel pump or fuel pick up sock issue at this point.

In reading about Bri3212 oil level question made me think. When i did the rebuild we changed out everything in the engine compartment from a sensor and relay standpoint, went through all the wire harnes, etc. BUT I never changed the sensor that is down on the botom end of the engineby the oil filter / cooler assembly. Isnt this an oil level safety switch? Does it throw a code when it activates?

Thanks for all the input folks

 

I think that one is just the sender for the gauge on the dash.
The one at the back of the intake is the fuel relay but that shouldn't be the problem anyway if the ECM sees distributor pulses, it will keep the fuel relay on that way.
No other real suggerstions except "DFCO" killing it.
Decell Fuel Cut Off setting in the bin.

 

I had this problem on my 88 Iroc. Ran fine, but acted like it was running out of gas upon hard corners. I replaced every oil seal and sensor (as I guess the computer thinks there's no oil pressure so it cuts the gas or something... forgot how it was put), cleaned every piece of the intake, new fuel tank, new sending unit, new pump, new lines...

Never solved the problem. Now the car lies in pieces in the driveway (and BTW, the new tank/sending unit/pump cost me almost $1000 and is for sale )

Good luck, and do let us know what happens!

 

First thanks to all who provided input, as this helped in finding my problem.

After much testing , I eleimnated any fuel related problems, presure, delivery, etc.

On the back of the block there is a sesnor that monitors oil presure ?

It has a small diameter tube that threads from the block to the sensor and in that tube some sealant had partly blocked the tube effecting the operation of the sensor. I found this when I removed the sensor to replace it.

I cleaned up the old sesnor and the tube and everything is running great

I pulled and cleaned the sensor that is down by the oil cooler as well but this one had no issues or anything suspect with it.

I have taken the car out 5-6 times and rode her hard and no cough, no stall, no problems and she idels right at the 600 - 750 range.

iIam happy

Thanks again

 

Yup, the can shaped thing on the back of the manifold is the oil pressure sending unit. So,your computer must have thought around corners that you had no oil pressure and cut the fuel!

Glad to hear all is well.