2002 Chev Venture - 3.4L Intermittant No Start

[Tim Martin]

I got this 2002 Chevy Venture with a 3400 engine and the problem is that extremely randomly the engine cranks over but will not start. The only pattern I can provide is that it happens, say the owner goes to town, lets it set for several hours and then tries to start it. Overnight it is no problem. The other clue is that it only happens if the front end is slightly upgrade from the rear of the vehicle. When it does start, it acts like it is flooded due to the amount of black smoke and missing and sputtering initially. After that, it is fine. No codes from the PCM. Has had new fuel pump installed due to customers request. I am puzzled. And becomming frustrated as the customer thinks that a solution should be easy because all I have to do is plug into the PCM and my machine will tell me what to do (so they think).

[brianp87]

Have you watched the fuel trims when it is happening?

[ricmorin]

If indeed it is flooding, I'd look at the possible causes........stuck open purge valve, leaking injector or leaking pressure regulator.

[Tim Martin]

If indeed it is flooding, I'd look at the possible causes........stuck open purge valve, leaking injector or leaking pressure regulator.

Well these are possibilities I also considered. Does being on an incline affect these components?

[ricmorin]

Perhaps the purge. If there was an incline issue that caused more fumes in the canister AND the purge was faulty. It's a stretch, but possible.

[brianp87]

I dont know what an incline would cause. Id look to be able to duplicate the sympton and take the readings and test from there. Its tough to fix something that cannot be duplicated.

[jbadenoch]

I'll bet the incline is not relative and possibly have a cam ar crank sensor if it's not fuel related. I'd have comp, fuel pressure guage and any other test equipment hooked up and keep trying to re-create the issue. Time becomes money

[ricmorin]

LOL. Yeah, I've seen that.

I have a drivability worksheet we use on less-than-obvious problems and one of the first questions is how often it occurs. I discourage customers who want me to look into problems at depth when it only occurs once every three weeks. I spend .5 only on non-symptomatic issues and advise accordingly.

Be careful.

[Tim Martin]

Well that is one of the frustrating issues I face here in our shop. Vehicles arrive with an intermittant issue and we are expected to diagnose the problem in a matter of a few hours or days at the most because after all, your machine you connect tells you the answer. It would be interesting to see a diagnostic worksheet that is used for intermitant issues.

I am also inclined to agree that the incline may have nothing to do with the problem although up to this point in time we have not proven anything so for now we are somewhat forced to include it as relative information, are we not?

[ricmorin]

Drivability Worksheet.pdf

worksheet

(15.84 KiB) Downloaded 346 times

Here is a pdf of our worksheet.

[steven kiser]

what about no spark but injector impulse causing flood. Try w.o.t. to see if it clears flood. possible injector sticking open but i don't think it would get that result. A sticking pump relay may force flood. If it only happens after warm up and the purge valves are clicking away it may be a fuel issue where fuel is being sucked into the evap system. Pull the vac feed hose off in intake during the no start to see if there's fuel in it. Haven't seen this in a while but when i did the first time it was a head banger.

[Tim Martin]

There ain't supposed to be fuel in the purge valve is there? If it is, we got us another issue

[ricmorin]

There ain't supposed to be fuel in the purge valve is there? If it is, we got us another issue

Nope. Fuel vapor only.

[Jeff @ Able Auto]

Sounds like ya might have a purge/vapor recovery system problem. Does the customer overfill the tank? Is this happening after a fill up and parked on the incline? With the cost of gas going up almost daily I see people trying to cram every ounce they can into the tank..maybe something to look at. Also look in the vapor lines from the canister for carbon particles. Had a ford some time back that was constantly overfilled. Loaded the canister with raw gas and over time the failures lead to the carbon getting into everything in the system.

[Tim Martin]

Which reminds me guys. I failed to mention that randomly there is a Code P0443 (EVAP Purge Solenoid Control Circuit) that appears. Is there any connection between this code and the intermittant no start problem? The last number of posts by you fellows might seem to indicate that. However, if I understand the code, 443 is an electrical code.

[steven kiser]

If the valve is stuck open you would get that code. In my little corner of the world the steel lines for the brakes and fuel will be ready to pop from rot. I believe there are three fuel associated lines. The pressure is obvious and would be real hard to cross not mentioning it wouldn't run but there may be a vapor and a return that can be confused. If infact it's related to raw fuel being sucked into the intake through a vac hose that's associated with vapor control there will be signs of raw fuel and if you can catch it when it's doing it pulling the vac line will show raw gas.

A few questions i would ask the customer would be if they key up the ignition and then wait before cranking it over. I've had customers that key up their vehicle adjust the seat, mirror, radio station, etc., before cranking over. I would also ask about any recent work done. Make a point it could be as small as someone replacing a blown fuse, air filter at whiffy lube, anything. I've seen all sorts of damage when Grape Ape got under a hood. Improperly installed alarms, remote starters, stereo's, tune up's, etc.. We've all seen wtf was this guy thinking situations. Look outside the box and ask questions like a Senate hearing.

One more quick thing here. I recall working on one of these and it had a few weird issues and i found the wiring harness damaged where it ran along the the inside of the radiator core support. I finally last ditch effort flipped up the outside fuse box to check for wires touching and chased the harness along the inside of the core support and found an area where it was all busted open.

[Tim Martin]

Ahhhhhhhhh. I may have found the problem with this one.

Right before lunch I took it to town to make a few stops. I got back to the shop, parked it insode and went for lunch. Came back and wanted to startit up and back it out - guess what? It cranked over good but did not start. Fuel pump was running, no spark and no injector pulse. Scan tool data showed no camshaft signal - so of course it wasn't gonna start.

So, I guess I'll be replacing a cam sensor on this one.

[steven kiser]

Hope this works. I can't see why there would be a lot of smoke coming out when it finally started if injectors were shut down. May be another issue with a stuck or leaking injector.

[Tim Martin]

Hope this works. I can't see why there would be a lot of smoke coming out when it finally started if injectors were shut down. May be another issue with a stuck or leaking injector.

Yes steve, there may actually be another issue yet. I will need to verify that before letting it go. I'm not sure how I will do that but I think my trusty lab scope and digital fuel pressure gauge should be able to point me in the right direction not?
Thanks for the input.

[jbadenoch]

Hope this works. I can't see why there would be a lot of smoke coming out when it finally started if injectors were shut down. May be another issue with a stuck or leaking injector.

Maybe as the cam sensor starts working again, its out sync and injecting fuel at wrong time then catches up. Just stabbing at it.