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Running only 3 seconds

Hope someone out there is patient enough to read through this.... (1991 4x4 pickup 4cyl.)

Problem started out as having to crank twice before starting. Then random hesitation while driving started, and became worse. During cold days, I had to crank 20-25 times to start (starter cranks fine). The gas filter was changed, the fuel system pressure was tested ok. Finally after replacing the Throttle Positioning Sensor, things appeared back to normal....but after a few days, a hint of hesitation and more than one crank needed to start reappeared (but no where near as bad as previous times). One day, the truck would not start at all. Checking out the fuel pump (because I previously had it rebuilt, and had suspicions), I discovered a severed rigid line on the output of the pump, so fuel was being pumped out, but hitting the flange and falling back into the tank - no wonder it wouldn't start. After repairing the rigid line and reassembling, I cranked the motor, and to my surprise, it started up right away! Unfortunately this only lasted for 2 or 3 seconds, then the motor died. Many attempts to start after this gave the same results - it would start up fine, run good, but only to die within a few seconds. I replaced the fuel pump, and have the same symptoms.

So, what could be the problem?

Terry

Reply to
DavisUnit
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My guess is that the fuel pump is only running while the key is in the START position. As soon as you release the key and it goes to the RUN position, the fuel pump stops and your engine stalls. It will start up again when you turn the key to START.

Someone here will know what makes the fuel pump run while the engine is running. I'll bet that is your problem

Ken - Dayton, OH

Reply to
RunnerBiker

| > Dave | | Thanks for reply Dave, but the fact that it runs smoothly for 3 | seconds would prove that spark is ok. | After reading, I'm looking at the air flow meter, and cannot figure | out exactly how to test it (there are 7 contacts). | The motor ran fine up to the point that the rigid line on top of fuel | pump broke, so I don't think dirty injectors would matter at this | point....they may affect performance, but don't think they would | prevent the motor from running (compared to it running fine before | fuel pump problem). | I have jumpered the B+ to Fp terminals, but see no improvement in the | motor running. | | Any help appreciated.

I would recheck the line where it was repaired and/or check the fuel pressure. It could be something clogged the line. Where is the fuel filter? Ahead of where you made the repair or after the repair? Having been there many times before, I have learned to double check things when I still have a problem. Good luck on it,

Jarhead

Reply to
Jarhead

That fuel pump is a bear! Jumpering the B+ to Fp, forces the fuel to run, right?

When MY AFM went bad, the engine died with NO error codes. First guess was ignitor; so now I have a spare ignitor ($70 worth!).

Desperate, I removed the connectors from the AFM and TPS, and, VROOM!, it RAN (not real good, though). Still ran with TPS hooked up, not with AFM. Got a used AFM from a later Toyota box ("16-Valve" FWD Corolla?), that ohmed out correct, at UPullIt for $15. Good-to-go ever since (2+ yrs).

Standard Motor Parts has a couple of techie articles on Toyota OBD I:

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Hope this helps! '89 4Runner 3VZ-E

Reply to
Ms. Manners

I think that "Runnerbiker" and then "Ms. manners" have it. I believe that the fuel pump has two states when it is relayed on: a blind "on" during startup and then a more conditional relay "on" during run time which depends on various factors.

Anyway, it's likely in the relay/control/sensing system for running the pump.

Steve

Reply to
Steve

I worked on a Nissan one time that had similar symptoms. Turned out to be the alternator was bad. The starting procedure would keep the motor running for a few seconds, but as soon as that stopped, the alternator supplied the juice to the fuel pump, and it was low, so the fuel pump would not run and the engine cut off. Owner neglected to tell me the alternator light was on and thought his problems were in the carbeutor. I'd check the voltage at the fuel pump while the engine runs and when it stops running.

Reply to
Albanygun

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