More diagnosing done....right track or no?


rusty ol ranger

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Ok....

Rechecked fuel pressure again. This time had a helper so i was able to read the gauge faster. Noticed some interesting stuff i missed before....

With a KOEO fuel pump prime, gauge would jump to 35-40lbs, but then drop to zero as fast as it climbed.

With a KOER running test i was only getting 33 lbs of pressure, but it would climb to 40 when the engine was revved. Yank the vaccuum line it climbed to 41 even at idle with no flucuation to speak of.

Thought maybe, just maybe it was a stuck open injector. Thought it was odd that would cause a lean code, but shit nothing else had made sense this far.

So, i unhooked the gauge, primed the pump, sat for a sec, and pulled a plug. Repeated this process for all 6. Not ONE was soaked with fuel, carbon fouled, nothing.

So i think i can rule out a stuck open injector.


Now, if it was stuck closed/plugged injector the fuel pressure shouldnt drop so quick...correct? I read the check valve is in the high pressure pump assembly, which is new.

I ordered a new FPR. Am i barking up the wrong tree with this conclusion? I read a few threads here and there that said FPRs dont always fail rich....

Input?
 


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alwaysFlOoReD

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You check the FPR for fuel in the vacuum line? Otherwise I think it would have to be a leak in a fuel fitting or the one way valve.
 

rusty ol ranger

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You check the FPR for fuel in the vacuum line? Otherwise I think it would have to be a leak in a fuel fitting or the one way valve.

Yes i did, it was dry. But i read a thread or 2 saying that they had failures withuut fuel in the line.
 

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The FPR can fail dry, but yours is working. A dry failure usually means the plunger is stuck (rotted fast) to the inside of the housing.

The FPR is the last thing the fuel passes before leaving the rail and going back to the tank. It is just a plunger on a spring with a vacuum diaphragm. Low vacuum (high throttle) and the spring overcomes the diaphragm, pushes the plunger down into the rail, and blocks fuel flow returning to the tank, which bumps pressure in the rail. High vacuum (low throttle) retracts the plunger allowing more fuel to pass, and drops the pressure.

The fuel check valve is in the filter-majiggy thing near the transfer case, or so I have always been told. Low fuel pressure, with a quick drop off, when the key is turned off is somewhat normal on a return-style system, but zero is too low. It should stop around 5 or 10. However low static KOEO fuel pressure will not cause an intermittent running problem, only hard starting. AFAIK you don't have that.

Also you are correct, a stuck open injector will not cause a lean code. It can hydrolock your engine though.

A sticking closed injector can cause all this. If the coil is weak or the pintle is stuck it may not be firing correctly, and would probably begin to show up more the longer you drive.
 

rusty ol ranger

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When i pulled the plugs last night cylnders 2 and 3 (back pass side) both plugs looked cleanish. Not like, steamed cleaned from coolant clean, but cleaner then the other 4. Actually all the plugs were way to clean if this thing is riching out like i originally thought. But when it acts up it acts like my old 77 did when the choke slammed clean shut. Not like its running out of fuel.

And no, it dont start hard. Fires up and runs always as easy as anything.
 

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the bleed down is likely just the check in the pump.


you are certain now that your o2 system is working correctly?

your tps is correct?

timing correct?

wires dont arc all over when you spray water on it in the dark?



did you replace the injectors with known functioning units...???

if not, having the injectors checked is something to consider.

vacuum and plug reads are very important for check point references. they can report more actual fact then a code scanner if you know what you are doing.

being certain the 02 is working correctly is the key to a obd1 map setup.

when you hit a rich limit in these earlier systems, generally it means that it is at its max enrichment factor and response is still not on the tables. with an improper functioning o2 system.... how the fuk is it supposed to know what is actually happening?

lean has an odor and eye burning effect too, and it is why it fools so many people. of course the black cloud is over fuel. you seem to have both intermittently and this would be on the variance of the on and off o2 function.

if the plugs are indicating cooking and or you are getting excessive knock, then lean from bad injector pattern combined with less then ideal timing can tear up the pistons....even on these nutless low power sewing machines...


without having the harness in my possession i hate to even try to guess anymore with what you are working with. i have seen too many of these get burned from exhaust blow out at the manifold connection and jank up the ohm values in the o2 circuit.
 

rusty ol ranger

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Never had any spark knock. No i did not mess with the injectors. I pulled the plenium off to do them, thats when i found the O2 wire, fixed that, and was hoping for the best. But it made no change.

I did look at the wires and things down around the exhaust/etc when i had the plenium off, the wireing looked good, to me anyways. No obvious burning/scorching. The wireing on this truck is pretty good yet, not butchered or rotted, all still in the plastic tubeing.

I do not know if the O2 is fuctioning properly, no. But i know i was having this issue before i changed the O2, but before i changed the O2 i was not getting and O2 codes. Now, with the new O2 i am. So im not sure if the old O2 wasnt doing its job, or???

That being said theres nothing in the wireing to the O2, besides that one i found, that looks suspect.

Like i said, its holding good vaccuum, and runs fine most of the time, even after it acts up its fine if you shut it off for 15 minutes or so. But the plugs do not indicate any kind of ignition issue, there not overly black or smell of fuel. The 2 back plugs i mentioned earlier had just a touch of combustion marks, so i dont think that those 2 cylinders are totally starved of fuel, but def not getting enough. Unless the other 4 are getting to much fuel, but they didnt look overly crispy.

I get so many contridictory signs off this thing its confuseing the hell out of me. It acts rich, but plugs indicate normal/lean. It runs fine untill its warmed up for a bit, then thats when it goes to acting up.

It burns no oil, the oil stays pretty clean, and it doesnt give me any indication the motor itself is unhealthy in anyway, shape or form. I may not know EFI, but a engine is an engine and i do know those, and i have no reason to believe im dealing with internal mechanical issues.

Also, like i said, it has a massive exhaust leak at the Ypipe to Cat connection, the gasket it about 75% gone. Its in very close vincinity to the O2 sensor, but it is downstream from the O2. Could that major of a leak, even being downstream, throw off the O2 sensor? Ive been putting off fixing that untill i got it running good, but could that be the reason its not running good?

As far as timing goes, i just had it done with the distributor dibacle i had. 10BTDC with SPOUT unplugged.
 
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RonD

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You can, carefully, clamp Fuel return hose closed, the one that comes out of the FPR, then cycle key on and off
If pressure still drops off fast then yes check valve is stuck open
If not then FPR is stuck open
Assuming fuel injector test was correct



An engine running rich will cause Cat to get really hot, and exhaust will smell rich
An engine running lean will ping/knock under load

If neither of these are seen/heard then gross air/fuel mix is OK
 

rusty ol ranger

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Would it still ping/knock with a knock sensor equipped motor?

If the knock sensor is pulling timing that would explain why its doggy at times. Never heard it ping or knock.

So the fuel line coming off the front of the FPR is the return line? I wasnt sure last night. Ok then, ill try pinching that off and rechecking pressure.
 

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hard to hear knock on a 2.9
 

rusty ol ranger

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It doesnt tick. If thats what youre gettin at
 

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Would it still ping/knock with a knock sensor equipped motor?

If the knock sensor is pulling timing that would explain why its doggy at times. Never heard it ping or knock.
hard to hear knock on a 2.9
That's why Ford did away with the knock sensor on that engine. They found that the sensor was confusing characteristic valve train noise with engine knock and pulling timing.
 

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Rusty,
My fairly new fuel pressure regulator just developed an external leak, but when I tested the pressure yesterday it was 41psi KOEO and didn't lose more than 2 psi after a few minutes. I swapped it with a 32 year old FPR and the pressure was 39lbs KOEO, but when I shut off the ignition, the fuel pressure would very quickly (about 4 seconds) drop down to nothing. Nothing was worked on but the fuel rail and FPR, and I pressure tested the complete fuel rail/injector assembly disconnected from the lower intake, so I know it's not the injectors. I have heard that the check valve is in the high pressure pump, and possibly the fuel tank reservoir, but not the FPR. Apparently it's in the FPR.
 

rusty ol ranger

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Rusty,
My fairly new fuel pressure regulator just developed an external leak, but when I tested the pressure yesterday it was 41psi KOEO and didn't lose more than 2 psi after a few minutes. I swapped it with a 32 year old FPR and the pressure was 39lbs KOEO, but when I shut off the ignition, the fuel pressure would very quickly (about 4 seconds) drop down to nothing. Nothing was worked on but the fuel rail and FPR, and I pressure tested the complete fuel rail/injector assembly disconnected from the lower intake, so I know it's not the injectors. I have heard that the check valve is in the high pressure pump, and possibly the fuel tank reservoir, but not the FPR. Apparently it's in the FPR.
I did buy an FPR, before this thread really got commeted on lol, so since i got it ill pry toss it on for shits and giggles.

I think this weekend im gonna do the wet plug test ron suggested a while back and see if those 2 and 3 injectors arnt injecting properly. If that checks out guess ill do a compression test.
 

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Rusty,
I swapped the new FPR back in after crimping all the way around the outside of the FPR with small vice-grips (where the two halves of the FPR join together). No more leak, and the pressure is back as it was before. No loss of pressure after 10 minutes, and only 7lbs lost after 1 hour. The check valve (if that's what it actually is) is definitely in the FPR.

Also, it appears that I have finally fixed MY stumbling, bad running problems that have plagued me for the last year or so. I did the fuel rail acid wash/soak and cleaned and rebuilt the injectors. It runs like it's supposed to now, and actually has some power that I don't remember it ever having (it's been running bad for a long time!). I am convinced after much reading and research (and definitely some good advice here at the Ranger Station) that ethanol is really bad for these old Rangers. From now on I'm either running non-ethanol gas, or using "Lucas Safeguard Ethanol Fuel Conditioner with Stabilizers" when I fill up. I'll be posting in the next few days what I did, what I used to do it, etc, because I have no doubt this is a common problem with these 2.9's due to ethanol "poisoning".
 
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