4Crawler

iTrader: (3)

Well, when it dies, is the fuel pump still running (with or without the test jumper)? Should stop when the engine stops (normally) but should still be running with the test jumper installed.

Double D

Filter. My bad. And i have it jumped. Drained old fule, put new fuel, now charging system. Will run for about 5 - 8 seconds.

Also, if I check for a code now, I get none where as before the CEL would flash consistently. I counted to 100 flashes and gave up. Now no flash after fuel filter replacement.

Double D

Ok i'm swapping the pump. Its in my gut. The longer I let it sit with the pump jumped and key on, the more reaction I get out of it. It sounds like its on, but I don't think its putting out enough pressure to run the truck consistently.

Double D

I decided to take a couple pics of the fuel pump and assembly. I'm not sure if the connections are what is causing the problem or if the pump just isn't putting out anough pressure but i'm leaning toward looking for a whole new unit not just the pump. What do you think?

Double D

So here we go again. I went 12 hours on it yesterday and at this point im stuck.
last night I changed the fuel filter. Same problem. However I do not throw any more codes.
I drained and dropped the gas tank, pulled the fuel pump and bench tested it.
I have solid 12 volts inside and outside the tank at all contacts.
Pump spews fuel like a super soaker water gun
tank now has new fuel.
i have good flow of fuel all the way up to the fuel filter
All my hoses and vacuum lines are in good shape (almost brand new) so I wanna say its not a vacuum line.

My guess at this point, having removed the filter and found nasty fuel is going to be the injectors are gummed up.

I have also heard that the TPS could be in effect here as well as the AFM itself. I think i'm headed for the injectors either way due to seing what was in the filter and knowing that this truck sat for a few years and "used" to run great.

xxxtreme22r

just for giggles, can you either remove an o2 sensor from it's bung or undo the exhaust before the cat? And try to start it?

Got to thinking about this and I had an exact same issue with a 2001 Hyundai Elantra that I used to race. Turned out I had a severely clogged cat. Probably from driving 6 months with the check engine light on. I took an o2 sensor out before the cat and it ran so I ended up gutting the cat.

Double D

would that not interfere with its performance while running on a soaked rag though. I suppose I can pull one but I would think maybe that it wouldn't run either way if that was the case???

xxxtreme22r

hmmm maybe your right haha, forgot about that rag thing haha.

have you tried pulling the saved codes? I know you had said the light was on at one point but.....

Double D

No I haven't. It didn't seem to know what was wrong when it "thought" something was wrong. It would flash continuously, not in sequence, but just a constant flash. Indicating SOMEthing might not be quite right but that it couldn't pinpoint the problem.

Double D

Actually, I don't know how to pull saved codes. I'm using paper clip method for the diagnostics.

Double D

I had two inifniti g20's a few years ago that had troubles like this when the AFM was bad or loose. I'm leaning more towards the injectors though because if I understand correctly, the AFM would still be part of the equation as well as the TPS when using the rag method. And I can't stress how well the truck ran when I did this. To me thats says fuel issues. And the only thing left I THINK in this situation would be the injectors.

xxxtreme22r

not that common though for all 4 injectors to gum up but anything is possible I guess. I would think it would only miss on 1 cyl.

Double D

Understandable that typlically only one would gum or go "bad" at a time. However this truck sat for about 6 years and the previous owner said it used to run great. He is a very reputable shop owner here in town and does all the work on the police cars so I can trust he is telling the truth to some degree. Problem could be that he tried like hell to start it on old fuel, and only clogged the system more upon doing so. Therefore, IMO all of them could have been clogged or even the fuel rail itself.

After more discussion here, I have come to the conclusion that the Air Flow Meter and the Throttle Position Sensor may not be ruled out on the rag method as essentially it has air and fuel and no other choice other than to fire up and run.

Double D

And again, as it stands now, with or without the jumper on b+/fp, it will start up, stabilize for 3 - 5 seconds, and choke out and die.

4Crawler

iTrader: (3)

That is "how to do it".

Maybe it is running on the cold start injector (only) if the other ones are not putting out enough fuel. Might be worth pulling them and sending them out for testing/cleaning.

Double D

Looks like i'm going to pull my injectors then. I can't see it being a BAD thing in any way shape or form. And that way i'll know my fuel system will be good for a long time as i've been all through it now!

Double D

I just replaced the throttle position sensor and the air flow meter and now i'm making progress. The truck will now run for about 20 seconds and very well i might add. Still if I hit the gas pedal, choke and die. If I don't touch the throttle, it will run smoothly until it gives up.

If I use the FP jumper, it starts up alot easier and smoother than without the jumper. I have an extra set of injectors that i'm going to run over to a shop here in town and have them cleaned up and tested and i'm going to replace the ones in the truck with those.

hnugen

Check to make sure all your vacuum lines are good. A leak will throw the AFM off and run like crap. I had a similar problem with my truck when I rebuilt the motor.

Another possibility is bad fuel left in the system. To completely evacuate it, pull the ignition coil, wrap a rag around the cold-start injector to catch the fuel and crack open the 12mm. Be careful, dont let it get in your eyes and dont spill anything!! Crank the car to prime out the system. Worth a shot.

Check the resistance off the TPS and AFM. Make sure the AFM door swings freely also.

Double D

ok i did remove the coil wire, open the cold start valve, and crank for a bit. What comes out doesn't smell like bad fuel anymore and looks clean. And if replacing the TPS and AFM, shouldn't that rule out readings from them? All of the vacuum lines are in great shape. I don't see it being a vacuum line but I suppose at this point, if i could "see" it would be fixed! I dropped of a set of injectors from my 86 to a shop to get em cleaned up and all and i'll get them back tomorrow. Is there a way to change them without removing the throttle body?

xxxtreme22r

I'm not sure, but you might wanna look into when toyota changed the injectors. you should be fine 86-88 but some of them had different resistances. Might wanna look into that.