sputtering engine??

stumpcatcher · Jul 7, 2013

Hi
86 Ranger 2.9Lt. I brought it home on a trailer from junkyard where it sat for 6 years, I was told it had unspecified engine trouble.
Since Im unfamiliar with fuel injected engines thot I would tell you what engine runs like. I just did oil change it ran the same b4 & after.

Hot or cold it starts fine.
When its stone cold, start it up and it runs like a new one, as it starts to warm RPM slows so I havta go turn up idle screw to keep it at 1000RPM, warms up a bit more RPM slows again and I havta urn up idle screw some more, and so on and so forth. When it gets to operating temp it sputters like its missing always in the same manner, give it some throttle and idle at higher RPM and it sputters exactly the same way no matter what RPM you run it at. When you step on it sounds like it runs fine till you stabilize it at a higher RPM.

I dont have a gas tank rite now so I stuck fuel line and return line in a 2 gallon jerry can and I overdosed gas with injector cleaner I ran it for about 30 minutes in total. I put a low pressure pump on the fuel line. I hear the high pressure pump run so I guess its ok. Fuel supply looks fine, when I push down on that valve stem looking thing where your spozeta check fuel pressure gas shoots out so I assume fuel pressure is good.

Assuming that all other things are ok, Is there something about fuel injection thats causing the problem??

stumpcatcher · Jul 7, 2013

Hey I just thot of something.........

Since it sputters like its missing always in the same manner, give it some throttle and idle at higher RPM and it sputters exactly the same way no matter what RPM you run it at. When you step on it sounds like it runs fine till you stabilize it at a higher RPM.

Maybe its timing chain slack?? :icon_confused:

RonD · Jul 7, 2013

Fuel injected engines use a coolant temp sensor called the ECT as the "choke", since there are no jets.
The ECT sensor tells the computer controller(PCM) that the engine is cold so the PCM runs injectors rich and advances the timing, just like a "choke" did on a carb.
This is called Open Loop operation.
The idle should be high, about 1,200, the idle is set by the IAC(idle air control) valve, this is found on the upper intake, it is a mechanical valve that is, in essence, a controlled vacuum leak, the more air it allows in the higher the idle.
The PCM controls this valve, but these do get dirty and can get sticky, cleaning them is fairly straight forward.

As engine warms up the idle is reduced and fuel mix is leaned out, the PCM then switches to Closed Loop, in Closed Loop the PCM uses the O2 sensors to determine if engine is running lean or rich and adjusts injectors accordingly.

The MAP sensor is located on the firewall, it will have a vacuum line attached, that's how you find it, the MAP sensor tells the PCM the air pressure inside the intake, this is how the PCM knows how much fuel can be mixed with the air, with flooding or stalling, the O2 sensors are for the fine tuning of this.
Make sure the vacuum line is air tight, a small leak will cause odd engine operation.

New Fords use a MAF sensor instead of a MAP sensor.

The ECT sensor is a TWO WIRE sensor and is only used by the PCM, there is also a ONE WIRE sender that looks similar, that one is for the dash board temp gauge.

When you stabilize the idle and get odd fluctuations it sounds like a vacuum leak, the PCM is try to stabilize it but can't.

Also check the fuel pressure regulator(FPR) on the fuel rail, it has a vacuum line attached, remove this line and make sure it is air tight and also doesn't smell like gas.
The FPR has a rubber diaphragm inside, and after sitting dry for a long time it might be cracked and leaking fuel, this would be sucked into the intake cause odd engine operation.

stumpcatcher · Jul 7, 2013

Haynes manual sez 1st thing to do I check the fuel filter.
That will take me the rest of the day.
Its the canister type, havta take canister off with band wrench, I dont have a band wrench that small, Ill havta jury rig something to take canister off.

stumpcatcher · Jul 7, 2013

RonD said:
Fuel injected engines use a coolant temp sensor..........................

WOW!!

Super info.
Thanks RonD

adsm08 · Jul 7, 2013

Oxygen sensor will do that.

Also, you don't touch the idle screw on an EFI engine.

Andy D · Jul 7, 2013

stumpcatcher said:
Hi
86 Ranger 2.9Lt. I brought it home on a trailer from junkyard where it sat for 6 years, I was told it had unspecified engine trouble.
Since Im unfamiliar with fuel injected engines thot I would tell you what engine runs like. I just did oil change it ran the same b4 & after.

Hot or cold it starts fine.
When its stone cold, start it up and it runs like a new one, as it starts to warm RPM slows so I havta go turn up idle screw to keep it at 1000RPM, warms up a bit more RPM slows again and I havta urn up idle screw some more, and so on and so forth. When it gets to operating temp it sputters like its missing always in the same manner, give it some throttle and idle at higher RPM and it sputters exactly the same way no matter what RPM you run it at. When you step on it sounds like it runs fine till you stabilize it at a higher RPM.

I dont have a gas tank rite now so I stuck fuel line and return line in a 2 gallon jerry can and I overdosed gas with injector cleaner I ran it for about 30 minutes in total. I put a low pressure pump on the fuel line. I hear the high pressure pump run so I guess its ok. Fuel supply looks fine, when I push down on that valve stem looking thing where your spozeta check fuel pressure gas shoots out so I assume fuel pressure is good.

Assuming that all other things are ok, Is there something about fuel injection thats causing the problem??

That is your trouble. You have tricked some old heap that somebody else gave up on SIX
years ago. Nothing is OK. On top of that youv'e completely hacked the fuel delivery. Be happy it runs . Use it to get your fire wood and fugeddaboudit

adsm08 · Jul 7, 2013

stumpcatcher said:
Haynes manual sez 1st thing to do I check the fuel filter.
That will take me the rest of the day.
Its the canister type, havta take canister off with band wrench, I dont have a band wrench that small, Ill havta jury rig something to take canister off.

That is not the fuel filter. It may have an element in it, but it's not the filter you are supposed to check. You are interested in the one all the way up at the front of the truck. Crawl under it right behind the front wheel and look straight up. It's an in-line unit.

stumpcatcher · Jul 7, 2013

adsm08 said:
That is not the fuel filter. It may.......

Ok, I seen it, working on it.
thanks adsm08

stumpcatcher · Jul 7, 2013

Andy D said:
That is your trouble. You have tricked some old heap that somebody else gave up on SIX
years ago. Nothing is OK. On top of that youv'e completely hacked the fuel delivery. Be happy it runs . Use it to get your fire wood and fugeddaboudit

Fuel delivery mimics original exactly.
This old heap is the newest truck I got.
I will to fix it, I got 2 wrecks with good parts that I need to fix it.
If I dont get it fixed by fall I can use my 85 Ranger 2WD to get wood, I made tire chains for it, and its ready to go. A Viking does not give up that easy.
As I will so shall it be.

sputtering engine??

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