Steve J.

Spent time prepping the '87 for a 2k mile round trip Dallas - Arizona for Thanksgiving. Tranny filter/ATF change, brake pads and rotors, air filter, fuel filter, etc. It's been running great. About 3 hours out, cruising at 80mph, suddenly began losing power as if it were starving for fuel. Limped into a gas station, stopped running, wouldn't start. Verified fuel pump working but still no start. Checked fuses. Installed my spare new relays for LH brain and fuel pump. Started right up, ran good and off we go again. One hour later, same thing - lost power, limped into gas station, wouldn't start or run. This time I didn't do anything, just waited awhile, tried again and it started right up. Sounded like it was running good but I felt like it was a little down on power. I didn't feel confident it could make the trip, so I parked it in Lubbock and rented a car for the rest of the trip. Trying to think what it might be. Seems to be temp related. Coil(s) maybe? LH ecu? I'm stumped.

SeanR

Steve, I might be wrong, but it sounds to me like a either a starved fuel pump or you've only gone the little one running. The wifes '90 did something similar as the external one went out, the internal one kept it running for a while, but would not be enough to keep the car running.

Steve J.

Sean - Thanks for your input. I'm 99.9% certain it only has one fuel pump, under the tank - but I will definately verify this. The problem is intermittant. Gotta be fuel, air or spark. MAF maybe?

killingmoon65

Sorry to hear about you failed road trip. My 78 did the same thing. Started and idlled good but lacked power under heavy acceleration and then stalled- again and again. It turned out to be the secondary pump under the fender. The engine runs with the primary pump under the tank but I don't think it has the pressure to feed the engine under load. That's where I would start looking.
Does kinda sound like a temp think too. Strange. Keep searching. You will find the problem.
Good luck.

marton

I guess you have done the flex plate?


Marton

ROG100

No intank pump on your car Steve.
Could be the pump seizing after getting hotter & hotter.
I have a pump we can put on there to get you home.
Is there any noise at all from the pump when its running?

Steve J.

Had my girlfriend bump the starter while I put my head under the tank and listened for the pump. It was making the same quiet buzzing sound it always makes. But I agree it could be seizing after heating up. It wasn't giving me trouble before I changed the fuel filter which was long overdue (50K mi.). Thought that would ease any strain on the pump. I'm pretty sure I can make it home from Lubbock - just wan't confident it could make the entire 2K mi. trip. Thanks for opinions - keep 'em coming.

michaelathome

Same exact thing happened to Wayne 2 years ago coming home from SITM. IIRC the in tank pump had failed and he was only running on the external pump. Make sure that you confirm that you only have 1 pump. From Seans experience and watching what happened with Wayne (S4) sounds like we have two pumps.

Michael

Steve J.

Just a followup post- Returned to Lubbock after a week to pick up Sharky. Started right up and ran perfectly all the way home and got 21mpg. I hate intermittant problems. Wish it would just fail so I could fix whatever it is.

ROG100

Hi Steve,
In theory you should only have an external pump.
Check if there are any wires leading to the boss where the pipe leaves the tank.
Roger

mj1pate

I have a fuel gauge from 928MotorSports that twists on with an interference fit to the end of the fuel rail. The slight fear of boogering up the fuel rail has given me cold feet, but the gauge will eventually be installed. I would suggest getting a gauge installed so that when you find it necessary to jump the fuel pump you'll know what your pressure is.

These symptoms in other cars are also associated with the Crank Position sensor (or Cam position sensor). Yes, purely inductive components may go bad, when the electrical bond between the pickup and the attached wire ages. I would replace these as a matter of course on 20+ year old cars.

Mike

Courtshark

Could be the LH; on the 87 I sold, the shut off and non-start issue it had got progressively worse. Meaning it worked fine for a while and then would inexplicably die and not restart. I replaced the ECU before selling it (thanks to JHowell37) and the problem went away.

WallyP

Any possibility that the tank venting system is plugged? Easy to check - just pop the fuel filler cap after running for a few minutes.

Steve J.

Wally - if one of the symptoms of plugged tank venting system is that I can never fill the tank completely, then that could be a possibility. Should I hear a whoosh when popping the cap after running a few minutes? I replaced the LH ecu and fuel pump about 5yr/65k ago. How much current should the fuel pump draw? I only have one fuel pump.

Hilton

Nice lateral thinking.

If complete filling isn't possible, then there's possibly a blockage or twist in the vent-hose that runs from the top of the tank-body, through the body-frame and on to the expansion-tank and ventilation check-valve.

If the blockage was further forward in the system than the expansion tank in the right-rear wheel well, then I'd expect you to be able to fill the tank completely (unless there's more than one issue at play here).