# 92 D21 Computer Fuel probs?



## mentawai69 (Oct 8, 2009)

This truck has 178,000 and I got it A YEAR ago.
Its been a good strong truck, about a month ago
I would hear the Fuel pump come on outta the blue.
The truck would be parked and you hear this hum coming from under truck near fuel tank. I thought the pump was going out> and let it be..the truck ran fine.. Untill one day it started surging at highway speeds, I thought that I better go get a fuel pump B4 it goes. Went to the parts store and the guy talked me into a tune up and fuel filter.. I replaced the parts, no dramas except the rotor was difficult to get off, pried it a bit and got it.. The truck ran fine a bit rough, but at least it ran.. I ran it to work after 10 miles it left me on da side of the road.Truck Would Idle but once you gave it gas would sputter and choke out.. got it towed, the mech said he thought it was getting too much gas and that he thought it was the computer> he said he tested the pump and it was fine.. well dunno if the computer can just go like that? and nothing else was effected, lights and all works fine..
i ordered a junked ECM and will try replace it.. any advice..


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## zanegrey (Dec 5, 2005)

the ecm can make the fuel pump stay on all the time..

but b4 replaceing it read the codes...


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## mentawai69 (Oct 8, 2009)

I have read the codes on 2 different sittings.
1st time said 21..
second time said 55.
The 21 code kinda blew me away. I stated thinking
Ignition probs..Crank angle sens etc.. dunno hope the ECM
does the job..
So whats the proceedure
Undo the old one and plug in the new one. start it up?


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## zanegrey (Dec 5, 2005)

what settings ??


if that ecm said 55 n e where then it is fine..

check the fuel pump relay on the inner fender well..


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## mentawai69 (Oct 8, 2009)

No I just had two different readings from the codes..
one reading was 21.
then a week later the reading was 55..
check the relay for what. I have unplugged the relay and
the truck eventually dies..
even with the 55 code the truck still would idle fine,
but seems like the truck is only firing on 2 cyliders..


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## mentawai69 (Oct 8, 2009)

So if you get a 55 code. does that mean the computer is good?
I am getting spark on all cyl. but the injectors are mucking up.
I thought not delivering fuel. But according to mech that looked at it
he said,"it was getting way too much fuel and thats why not firing?
and that it could be the comp...
How to check da relay.. i pulled it while truck running and the truck eventually died..


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## zanegrey (Dec 5, 2005)

generally speaking if the ecm is giving 55 then it is good..

just pulling the relay may not be enough..















just about everytime i run into one that the injectors spray all the time it has been a bad ecm..but that is not to say that is ur trouble..



do you have one to swap out?


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## mentawai69 (Oct 8, 2009)

I just checked the codes again, got 55 in mode 3..
Truck still runs like hell.
In mode 4 the red blinks and stays on, and mode 5
the red blinks.
The relay .. what more can you do to the relay. change it out?
how about fuel regulator.
I thought that when changing the fuel filter that some dirt
got past the filter and could have effected the injectors.
But the mech I had it at said the injectors are spraying too much.
he got that from pulling the plugs and an ohm reading at the injector.
the ohm reading was 20 ohms.


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## zanegrey (Dec 5, 2005)

just swap the relay with another green one..

i have those ecms if you cannot find one..

there should be a fuel pressure reg close to the fuel rail..


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## mentawai69 (Oct 8, 2009)

Could the crank angle sensor have gotten damaged when I had to pry the rotor off.
I wonder if this could make these symptoms?


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## zanegrey (Dec 5, 2005)

if you are getting spark then the cas is working correctly..

and didn't the prob come up b4 u did the tune up???


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## mentawai69 (Oct 8, 2009)

B4 the tune up was just the fuel pump coming on and a bit
sputtery at high speeds.
after the tune up the cylinders started not firing.
Im guessing that only 2 clynders fire right now.


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## zanegrey (Dec 5, 2005)

read the codes and confirm the spark ..


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## mentawai69 (Oct 8, 2009)

Zane, I cleaned up some grounds and pulled the fuel relay banged it around and sprayed elec cleaner on the CAS the truck took a while to start, But when it did It was running on all cylinders and I am getting the 11 code in Mode 111. what now?


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## zanegrey (Dec 5, 2005)

if it is running well now just reset the codes, recheck later and send me a check...

if it is not you broke the dizzy ..

i think i have those dizzies for sale..


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## mentawai69 (Oct 8, 2009)

I drove da truck and re checked codes, back to 55.. runs good, a bit backfire.
But the tach goes bananas, hits 4K when it should be about 2k and doesnt go above 4k.
whats da dizz..
what do you rekon I had an intermitant ecu failure or?
I really didnt do much more than pull the relay and unplugged the Crank angle sensor.


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## zanegrey (Dec 5, 2005)

distributor = dizzy..

go back and use some white lithium grease in the connectors..

sounds like you have a kind of crappy connection..


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## mentawai69 (Oct 8, 2009)

Can you use white lithium grease as dielectric grease.
I thought its non conductive?


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## zanegrey (Dec 5, 2005)

it helps keep it clean over extended time ..


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## brookwood61 (Aug 18, 2005)

I know when my ECM ground was bad, the truck ran like crap, at times. It would run great, then fall on it's face for a while. I pulled it out from under the seat, and grounded it right to the floors with 2 ground straps. 
Good Luck


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## mentawai69 (Oct 8, 2009)

Does the ECM ground through the mounting Bolts?


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## brookwood61 (Aug 18, 2005)

zanegrey said:


> distributor = dizzy..
> 
> go back and use some white lithium grease in the connectors..
> 
> sounds like you have a kind of crappy connection..


I'm glad to see someone else uses white grease on connections. I've been using it this way on vehicles, model trains, outdoor lights, etc., for a long time. It has never let me down.


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## brookwood61 (Aug 18, 2005)

On mine it was just laying there-not good. I used generic strapping, and used self-tapping screws to each side of the box, then the other end of the strap to the floors. Just watch you do not hit anything inside the box. I have a king cab, so I had the room behind the seat to mount it.


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## brookwood61 (Aug 18, 2005)

mentawai69 said:


> Does the ECM ground through the mounting Bolts?


Sorry, I misread your question(cat wanted fed-top priority here, or no peace). No, it should have a harness ground. Mine was probably bad, and when I grounded the box, it corrected it through something connected inside the box, to the box.


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## mentawai69 (Oct 8, 2009)

Shoots, I replaced the ECU with one from JYD.com 75 bucks.. and a new fuel relay.., I got plenty of fuel, but now have no spark..
this whole prob. has slowly appeared. this truck used to run.. then went to just an idle.. when you give it gas it would act like it was firing on 2 cyl. I opened the Crank angle sensor, sprayed elec, cleaner on it.. then it ran fine.. but the tach went crazy too high.. well now.. truck does not start. and no spark/// should I start with Coil.. or crank angle sensor.. or Dizzy?


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## zanegrey (Dec 5, 2005)

go back to ur last ecm to get your spark back and see if the jy will let you swap it out for one that works correctly..


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## mentawai69 (Oct 8, 2009)

Whats da JY.. I might have lost da spark B4 the swap..


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## mentawai69 (Oct 8, 2009)

I changed the ecu, they both the same irratic weak spark. When checking spark from the coil. while engine was cranking no spark. then as they turned the key off. engine not cranking but the key on the wire was sparking uncontrolably..?? and a good spark.. shoked the shit outta me.. what does this sound like.. coil. CAS ???


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## zanegrey (Dec 5, 2005)

try to explain that differently please i am not tracking...

jy=junk yard...


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## mentawai69 (Oct 8, 2009)

You might remember all along i thought this was a fuel problem. I thought the Injectors were injecting too much fuel..
At the begining of prob. the truck would Idle, then when you hit the gas would cough and sputter acted like only 2 cyl were firing.
I ordered an ECU from JYD, while waiting for delivery I sprayed elecctrical cleaner on the Crank Angle Sensor, unplugged it etc.. after that the truck ran fine, I drove it a couple of miles near the house. The only thing is the Tachometer was going crazy, too high of a reading.
I then tried to start the truck the next day, and nothing. No start.
I checked the spark and it was irratic and weak..
I put in the new ECU. The truck doesnt start. still irratic and weak spark.
Then on one attempt to check the spark. my wife was cranking the engine.
While it was cranking I did not get a spark at all and as she stopped cranking i got a huge series of sparks, good blue sparks rapid. And this happened when the key was on but not cranking and continued until the key was turned off.
I dont know if this is a problem with the coil/the crank angle sensor or ? I did do a test on the CAS and it was getting 12 volts at the A tab with the key turned on..


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## zanegrey (Dec 5, 2005)

that is a bad ecu as well...

or you have some wireing issues..

just to the front of the ecu is a blue block of wires..

check it to see if it is corroded or damaged...


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## mentawai69 (Oct 8, 2009)

I pulled the blue plug connector and it was clean, pulled the white one and was corrsion, I cleaned it tried the truck, still low spark.. it tries to start but doesnt..


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## zanegrey (Dec 5, 2005)

the connector is not the blue block..


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## mentawai69 (Oct 8, 2009)

Which one is it Brother.. I see now that there is a smaller block up by the center/stick shift area.. that has been duck taped to the body.. maybe some prob there?
Would you recomend replacing the wiring harness..


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## smikster (Aug 12, 2008)

did you ever redo the dizzy? just kindu skimmed threw here...had the same prob...dizzy was very grumpy! mess with it a bit


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## mentawai69 (Oct 8, 2009)

What else can I do to the Dizzy. 
Went from A Running vehicle,I did a tune up. 
The truck slowly lost fire in cylinders. would only Idle/ you step on it and it would sputter bad.
I sprayed Electrical cleaner on the Crank Angle sensor/ then the truck ran fine, all cylinders fired perfectly..
The next time I went to start it.. no start.. I checked spark. no spark erratic weak spark..
Everyone has been telling me ECU Bad, Injectors clogged..
After spraying the CAS with cleaner i figured the injectors OK.
and I changed the ECU, no change..


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## smikster (Aug 12, 2008)

check/clean your maf...xxxxx.....never hurts


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## mentawai69 (Oct 8, 2009)

Sorry But whats a maf xxxx


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## smikster (Aug 12, 2008)

if you look at your intake the little hole on the left...

take it off and clean it with some elc cleaner or brake cleaner...if your gutsy a q tip very softly on the wires.


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## mentawai69 (Oct 8, 2009)

Roger that, Thanx. whats up with a grumpy dizzy, what can I do.. I am getting a better spark now.. but still weak and yellow spark.. but at least it is sparking more than before


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## zanegrey (Dec 5, 2005)

maf= mass air flow sensor mounted on the side of the ventura..

check the connections for the dizzy ,all grounds and fusible links..
check cap and rotor.. clean plugs..

check wires to coils and ballast also check their connectors..


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