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Truck won't start


Nic

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Hey all. I have a 91 ranger, 4.0 and it was giving me fits last night...seemed like a nasty throttle issue. So I go to work on if this morning and now it hardely starts and when it does it dies about instantly. So now I'm here beating my head against the engine trying to figure out what's wrong with the damn thing. The linkage isn't blocked or anything, I was thinking maybe TPS?
 


RonD

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'91 4.0l will have a MAF(mass air flow) sensor, this is the main sensor to determine fuel mix.
TPS sensor is for quicker response time, like the accelerator pump did on a carb.

You didn't described your symptoms, so just shooting blind here.

If MAF has been cleaned then it could be low fuel pressure or clogged exhaust.
Fuel rail should have 35psi of pressure, more than a tire's pressure.

Usually with clogged exhaust it will start and idle OK but stall out when trying to increase RPMs, low fuel pressure is almost the same symptom.

Bad TPS shouldn't cause a no start, and check engine light(CEL) will come on.

Computer doesn't use many sensors to start and idle.
MAF, IAC(idle air control) valve and ECT(engine coolant temp) sensor are about it.
ECT is a 2 wire temp sensor that only the computer uses, it is like the Choke for fuel injection, if ECT shows cold computer runs engine richer with higher idle(IAC Valve opens more)

Spark on the '91 4.0l is self contained, it uses a EDIS-6 module(on rad support) and a coil pack, these rarely fail, EDIS module does send timing pulses to computer to sync fuel injection with spark, but no pulses would = no start, not hard start.
 

Nic

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Hey, thanks for the ideas. It will start, very reluctantly, and then die immediately after start. It feels like it is getting fuel, and then that supply goes away. On a different post, I don't know where that went, I described how we checked the TPS and saw it was good, and then found that now power was getting to the injectors. So now the question is why?
 

RonD

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Fuel pump is dieing
You need a fuel pressure tester to confirm
Dirty Fuel filter will usually allow engine to idle but limit RPMs, no start would be the pump most likely.
 

freedom5

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Read my post under 2.9 liter and "Un-thought of" Solution. I am amazed how smooth and good my 2.9 is starting, running and accelerating after cleaning the corrosion from the fuel pump relay contacts and replacing the relay. It used to falter when I tried a rapid acceleration and or depressing the accelerator under a load. It now runs like a new engine. I kept trying all other solutions until it finally failed to start and discovered it wasn't getting any fuel.

The only answer appears to be the corrosion n the 27 year old relay was preventing the fuel pump from getting enough voltage. It now starts immediately, doesn't have to wait until the engine warms up to put in gear and no more hesitation.

Hope this helps all who are having similar problems.

Freedom5
 

Nic

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Ok, thank you all very much!! Pulled the filter, and it was filthy and full of water. So I'm going to replace the filter and I put some water absorber stuff in the tank. If that doesn't work, to the fuel pump I go
 

Nic

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Hey all! I replaced the filter, and it still won't run. A couple days ago when I started to try to figure out what was wrong, the fuel pressure was fine. Now, it has almost no pressure and a ton of air in the line. So I'll get a fuel pump and replace that, and hopefully my poor truck will be all ready to go after that! Thanks for all the help!
 

AllanD

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it typically takes multiple cycles of the key to purge the air from the fuel lines
and re-pressurize the fuel system after replacing the filter
 

Nic

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That makes total sense, thanks. I did that, but I can't get any pressure at all. It's a 23 year old fuel pump, I'm very impressed it had lasted this long!! So I guess that everything fails in time
 

black_demon69

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That makes total sense, thanks. I did that, but I can't get any pressure at all. It's a 23 year old fuel pump, I'm very impressed it had lasted this long!! So I guess that everything fails in time

if you end up replacing fuel pump STAY AWAY from AIRTEX they are junk, and pull bed not tank much easier..
 

Nic

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if you end up replacing fuel pump STAY AWAY from AIRTEX they are junk, and pull bed not tank much easier..
Ok, thank you! Ok, I've heard of pulling the bed, but how exactly do you do that?
 

Nic

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Ok, thanks! I've heard about pulling the bed, but how exactly do you do that
 

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Pull the turn signal lenses out and remove the connectors from them, feed them down through the bed to the ground.
Take the three screws out of the fuel filler neck.
Unscrew the 6 round headed torx bolts on the floor of the bed.
Then get a buddy to help you lift the bed off because it's too awkward to remove alone.
Then the top of the tank is easily accessible.


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you could do what i did, I had to replace the fuel filler hose and on my truck the bolts were rusted so bad I was going to have to replace them all. when i took the bedliner out there was 2 huge rust holes right above the hose. so i got a nibbler and cut a flap big enough to do the work i needed to do. I ended up putting an aluminum sign over the hole and pop riveting it. put the bedliner on and nobody knows. I've seen many people do this to replace their fuel pumps. It all depends on what shape your truck is in. I'm only going to keep this for another year probably, and with the holes that were in it, it didnt bother me at all to make them bigger.
 

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black_demon69

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Pull the turn signal lenses out and remove the connectors from them, feed them down through the bed to the ground.
Take the three screws out of the fuel filler neck.
Unscrew the 6 round headed torx bolts on the floor of the bed.
Then get a buddy to help you lift the bed off because it's too awkward to remove alone.
Then the top of the tank is easily accessible.


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or you could tilt bed back like dump truck and block it up

1 remove bed liner (if you have one)
2 remove 3 filler neck bolts
3 remove the 4 t55 bed bolts toward the front of truck
4 loosen 2 bed bolts at the rear leaving them threaded in just a few threads
5 get helper and tilt bed back and block it up
6 relpace fuelpump
7 reinstall bed in reverse order of above steps

when i did my fuel pump it only took me approx 45 min for the job
 

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