I'm back with a question

[FirstRanger86]

EFI cousins: I am sorry for the non V8 content.
I bought an 86 2.9 Ranger at an auction a couple of months back. I was thinking V8 swap right off the bat, but to my surprise, it started right up, even missing one spark plug wire. It had a lot of mouse poop and some chewed wires, but I cleaned it all up, put some money into tune up parts, and it will not stay running. This OBD1 is driving me crazy.

A few folks here said it would be almost plug and play to go 2.9 --> 5.0 and keep the EFI. So I'm hoping someone here can help figure this out.

New: belts/hoses/thermosats/fuel and radiator caps /plugs/wires/cap/rotor/master cylinder/tfi/fuel pump relay, all filters.

Symptoms: starts right up, goes to high idle, comes back down to idle, idles for a minute or , then dies. Hard to restart, can keep it running, and get into normal operating range by holding RPMs at approximately 2500 (no tach). Eventually, cuts out and can not re-start until cooled (completely). Once ice cold, starts right back up. Oh, and to confuse matters more, once it does start to warm up, some black smoke (rich?) from the exhaust, but none at startup or when cold.

I hate throwing parts at it, but a friend said why not do the TFI, so I did (KEM brand and I put the the grease on it).

Has anyone had a similar problem and not have it be the TFI? I don't think it's fuel pumps/pressure, as it can rev pretty good, when it is running.

The only other piece of information I can give is that it was giving a code 31 on the KOEO test. I had the battery off all night to reset that, as I found a chewed wire going to the vacuum solenoid on the passenger firewall (supplies the EGR).


Thanks in advance for anything that might help me get this thing rolling.

Tom

 

[alwaysFlOoReD]

So your engine is running fine on the pre-set and crapping out when the sensors come online. o2 sensor? Sounds like it's running on open/closed loop [I can't remember which is which]. The computer has pre-set values that runs the engine until it warms up, then the o2 and other sensors tells the computer how much fuel to put in. change the o2.
Good luck,

Richard

 

[FirstRanger86]

So your engine is running fine on the pre-set and crapping out when the sensors come online. o2 sensor? Sounds like it's running on open/closed loop [I can't remember which is which]. The computer has pre-set values that runs the engine until it warms up, then the o2 and other sensors tells the computer how much fuel to put in. change the o2.
Good luck,

Richard

Thanks, Richard. I guess it absolutely could be; the sensor is probably welded in there with rust. Same could be said for the MAP sensor, though, no? Would a bad 02 sensor throw a code on KOEO, or KOER?

Thanks!

 

[FirstRanger86]

Ok, got an important piece of information today, not sure what to do with it.

I got a working fuel pressure gauge. Started right up, pressure held at 30 psi for about 75 seconds. It then began to slowly drop, and as it got lower, the engine picked up idle to try to keep running, and it finally stalled somewhere under 6-8. I did key on-off to build pressure in the rail to about 16, it started, but never went over that 16 or so, dropped down, and stalled. Did this a couple more times, always the same thing.
Are my pumps shutting down? What would do that?
Is a pump bad, and failing when it heats up? Which one?
Why does it work fine when ice cold and start after warming up a tiny bit?

Getting closer...I think!

Thanks for all the help...please help me get there

 

[ashleyroachclip]

I would look at the fuel pressure regulator , make sure the vacuum line to it does not have gas in it.
The regulator is easy to replace and cheaper than a fuel pump.
If you determine the fuel pump is bad, I recommend lifting the bed to change it ,rather than trying to drop the tank to change it.

 

[RonD]

The high pressure pump on the frame rail was added when fuel injection was added.

I would test the FPR(fuel pressure regulator) first.
Start engine with pressure gauge hooked up.
get a stable pressure then pull off the vacuum line on the FPR, use finger to plug the end of the hose so no vacuum leak on the intake.
Pressure should jump up on the gauge as FPR closes, vacuum at idle holds FPR open all the way, removing vacuum closes it, just like it would be when driving at higher RPM, when vacuum is low.

If pressure doesn't jump up then replace FPR, if it does then test for power at the high pressure pump, there is a splice near it where power is taken from the original wiring for the in tank low pressure pump, if that is corroded then high pressure pump may have less than 12v or intermittent power.
Or replace high pressure pump.

Also don't forget about the fuel filter, you didn't mention that being replaced specifically, it can limit pressure after start up.

 

[FirstRanger86]

Thanks, Ron, that's very helpful. I will do all that and report back. I definitely have power at the high pressure pump, and it stays consistent as the truck runs and stalls. I did replace both fuel filters, so if the regulator is OK, I will swap out the high pressure pump.

Thanks a ton!

The high pressure pump on the frame rail was added when fuel injection was added.

I would test the FPR(fuel pressure regulator) first.
Start engine with pressure gauge hooked up.
get a stable pressure then pull off the vacuum line on the FPR, use finger to plug the end of the hose so no vacuum leak on the intake.
Pressure should jump up on the gauge as FPR closes, vacuum at idle holds FPR open all the way, removing vacuum closes it, just like it would be when driving at higher RPM, when vacuum is low.

If pressure doesn't jump up then replace FPR, if it does then test for power at the high pressure pump, there is a splice near it where power is taken from the original wiring for the in tank low pressure pump, if that is corroded then high pressure pump may have less than 12v or intermittent power.
Or replace high pressure pump.

Also don't forget about the fuel filter, you didn't mention that being replaced specifically, it can limit pressure after start up.

 

[FirstRanger86]

Well, I'm starting to hate this truck, and it hates me.

I checked the regulator, unplugged it and my steady 30psi fuel pressure went to about 40. Done. Changed the high-pressure pump, ate a lot of rust and who knows what else, connect the battery and.....same deal.

Warms up for a minute or two, pressure drops, stalls. It appears the high pressure pump was starving for fuel, thanks to a low pressure pump that is failing. Ordered the low pressure pump, now scheming on how to get the 6 torx bolts out that hold the bed on.

 

[Rowdy Fitzgerald]

Squirt them with wd40, pb blaster or what ever you have. Let it set for a while, wire brush the ones you can, hit them with more lube then bust me loose with a breaker bar. Then just use a impact to speed up the removal.
That's how I got mine out.

 

[FirstRanger86]

Thanks, RF. It's hot as hell today, and I had little time, but I squirted the back four with PB blaster and gave them a shot with the impact gun and the t55. One came right out, one clip broke, and the rest wouldn't budge. On the front two, I couldn't even see the clips underneath to spray anything. I will get the breaker bar ready for later.