Furunner

Hi 3.0 aficionados. Here is a no start saga that is leaving me clueless.

SYMPTOMS
- Random No Start but cranks endlessly.
- Progressively getting worse (more common) over the last 4 months and now will not start 98% of time.
- Would almost always restart after sitting for a few hours or overnight (until last few weeks and now will rarely start)
- Runs/Drives fine once you get it started
- Will not die while driving UNLESS it has been descending a big hill or mountain pass where no gas has been given for a long period of time, at which point it dies at the bottom of the hill if you bring it to a stop at a stop sign or something. Then it cranks endlessly like all of the other times.
- I have started it successfully 2 times with starter fluid sprayed into air box but even that is unsuccessful now not to mention bad for motor.

FUEL - New Fuel Pump it works fine and has been driven several times since install. Also, I can hear it running when touching a jump wire from FP to B+ in the diagnostic box. New fuel filter. Fuel pressure at fuel rail is 43 PSI. New fuel pressure regulator as the old one was found to be faulty and would not hold vacuum and was pulling fuel inside of it, no change in symptoms with new one. Replaced fuel pump relay. Replaced EFI relay.

SPARK - Has spark from igniter/coil to distributor and has spark from dist. to wires. New wires and plugs.

AIR - Mass Airflow Sensor seems to be fine, the valve inside of the airbox opens and closes as it should. New Air Filter. O2 sensor tested at 2.12 volts at running temp which is incorrect but I'm having trouble believing that this is the issue but maybe?

COMPRESSION - Had a compression test done at a reputable shop in March and the compression came back good.

Could Timing belt be off? Cold start injector or other fuel injectors stuck open? I'm at a loss, any info is so appreciated. Thanks for reading

. . . There has to be something to the issue of it dying at the bottom of hills after no gas has been given for a long time, right? What am I missing?

Nick

jbtvt

So it sounds like it's losing fuel most likely? If I were you the first place I'd start is bypassing the AFM switch/circuit opening relay. Jumpering +B and FP will do this. Proceed at your own risk on this of course, and be aware that fuel will continue to pump as long as the key is "on". If this solves the problem you can proceed to isolate which component is bad.

Furunner

Jbtvt, I have changed the Open Circuit Relay already. Also, when placing jumper on FP to B+ I can hear the fuel pump running but still no start so I had ruled out the Open Circuit Relay as the cause, but if I missed a step in that process please let me know and thanks

fdp101452

I would pull some spark plugs next time it wont start and see if they have fuel on them. You say you have spark, but I wonder what kind of spark you are getting. What were the compression numbers? Why do you think the timing belt might be off?

jbtvt

^x2 on checking the plugs. Strange problem, please update when you figure it out/work on it.

Furunner

Pulled one of the plugs (should have pulled more but didn't have time) after cranking for about 20 seconds. It was dry. A friend and I got some weird results from the oxygen sensor. We got the truck to start once (About 1% of the time it will start) and tested the oxygen sensor in the diagnostic box, it failed its test with the voltimeter and was reading anywhere from .86 to 2.45 with the numbers changing along with the wandering idle - if you watched the voltimeter as it was idling. My friend removed it and got the truck to start, he cleaned the contacts and was getting it to start and run really nicely so a new O2 sensor was put on and now it will not start again adding to the frustration. I'm going to play around with the O2 sensors a bit more. My next step I think will be to check each spark plug and each individual fuel injector. I'm also still skeptical about the timing being off and the ECM being bad among other things. Still a mystery though.

vasinvictor

iTrader: (3)

Did you get a good fuel pump or an autozone lifetime warranty pump? Sounds very fuel pump-ish though you said your pressure was good.

Furunner

No not a top end fuel pump but it's hard for me to buy top end parts when I'm installing them on a hunch, that gets expensive quick. But I have good fuel pressure at the fuel rail so if it's a fuel issue that narrows it down to the injectors right? I'll be testing those next along with the cold start injector.

Furunner

If it does somehow end up being a FP issue I cut a hole in the floor of the backseat for easy access to the pump so I don't ever have to remove the gas tank again.

RJR

When you say it no longer starts "successfully" using starting fluid, do you mean...
(a) It won't fire at all even with starting fluid, or
(b) It fires when using starting fluid, but won't keep running once the fluid in the intake is used up.

If it's (a), it sounds like an ignition problem
If (b), you've got a fuel problem. Since your fuel pressure is good, I'd suspect a problem with the injector pulsing. I would try to observe the signals from the ECU to the injectors while cranking. Use an oscilloscope or a noid light to tell you if they are pulsing.

The O2 sensor should not make a difference, as the ECU ignores it during starting and warm-up.

Furunner

RJR, "B" is my problem. It will start with starting fluid but once used up it will die. I believe that you are on the right track with the injector pulses and they are what I will be checking next. Currently the cold start injector is off and being checked.

Kiroshu

Check EFI Relay.

-Damage
-Corrosion
-Moisture
-Fault

Furunner

Checked and replaced the EFI relay already. It's looking like the culprit is the cold start injector (I say this with great reservation given my luck with this issue). I have a friend working on it right now who is a great mechanic and he removed the cold start injector which was apparently clogged and not spraying at all. He soaked it in sea foam and cleaned it and it sprays nicely, the vehicle starts up every time now. I'll post a full report after I grab it from his garage tomorrow and talk with him in person.

vital22re

iTrader: (2)

I would suggest cleaning all the injectors. They sound tired and dirty. And it sounds like the ecu was having a hard time keeping the mixes right with dirty injectors and faulty o2. I wouldn't be surprised if the catlytic converter is clogged up as well. Maybe why it ran with out one installed.

jbtvt

Not to be a downer but I wouldn't get your hopes up with the CSI. It only speeds the starting process mildly in all but the coldest weather and definitely wouldn't kill it while running.

If you've got fuel pressure but the plugs are dry it sounds like RJR is on the right track with checking pulses. Apparently the ECU has a small fusible link, if it comes down to it don't toss it without checking that.

Furunner

UPDATE! Ready to really scratch your head?

Truck has been running great for the last week and 500 miles. Idles great, starts every time, runs better than ever!
Between cleaning the clogged cold start injector, a new o2 sensor, returning vacuum to the charcoal canister (someone had bypassed it at some point), and connecting a disconnected EGR line in the back of the motor (large L shaped line that had also been disconnected for some reason) the truck has been awesome. The idle was slightly adjusted as a finishing touch. Ready to scratch your head?

I didn't mention this before because I thought it was a separate issue. The transmission (auto) had not been shifting from 2nd to 3rd gear and would go into neutral. It was getting very bad and I had already purchased new solenoids for my next project. Well after the no-start and idle problems were corrected, magically so was the transmission! It has had zero problems shifting for the last week! Yesterday while driving the low Lopey idle came back, the same transmission issue came back simultaneously and when I parked it and shut it off - you guessed it . . . No Start! Any ideas on how the tranny could be connected to any of this? I'm puzzled.

Furunner

I should also mention that through all of this I have had a code 71 for EGR malfunction. This code was given even during time it was running fine.

vasinvictor

iTrader: (3)

What about ECU? More specifically power or grounds. Loose grounds seem most likely. Just trying to come up with a shared component.

Furunner

Thanks, I'll definitely check the ECU. Could a vacuum issue tie these all together as well?

vasinvictor

iTrader: (3)

The ecu is ect (electronically controlled trans) so I doubt it. There are a few very important grounds in the engine bay. From intake manifold to firewall and from battery to firewall. Another from battery to lower block. Might pull off the ecu cover and see if you can find anything that looks out of the ordinary. Loose connectors, loose grounds, etc etc. If everything looks in order I'll bet you could find a really cheap ECU at a boneyard or eBay to swap out. Never really seen a confirmed case of an ecu going bad but after all electrical components can fail especially after warming up.