2005 Pontiac Montana hard start when hot - Page 6 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 12-09-2011, 11:03 PM   #51
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My Montana is a SV6, it'* different.
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Old 12-09-2011, 11:36 PM   #52
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that eng is listed in the 2006, that last link I posted, fpr part of fp assembly! Thats a new twist!
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Old 12-10-2011, 10:38 AM   #53
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Yep, somehow I ended up with a odd ball. Can't tell you how many times I've gotten the wrong parts. Well, that'* what the computer says. Don't care, it'* a SV6. Oh ya, it is different.
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Old 12-16-2011, 10:34 PM   #54
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Well my problem seems to be the same as Dan'*. In the morning (on cold) is all good when I turn the ignition on, however, as soon as it gets hot turn it off and turn it back on within 15-20 minutes the hard start problem begins. I have to hold the ignition on for 5 or more seconds for the van to start, sometimes I even have to help it out by holding the gas pedal a little just so it can get over its weak start. But then again If a let it sit for no more than a minute or two it starts like nothing ever happened. So what gives?
It is a 1998 Trans Sport Montana V6 3.4L
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Old 12-16-2011, 10:53 PM   #55
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Check your fuel pressure regulator. Pull the vacuum line and smell it. If you smell gas, the FPR is bad.
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Old 12-17-2011, 02:37 PM   #56
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Thanks. I'm about to do that now. I'll reply later to let you know the outcomes.
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Old 12-18-2011, 08:57 PM   #57
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Quote:
Originally Posted by Danthurs View Post
I also noticed a little surging when in cruise, and this is a symptom of a bad crank sensor.
Surging can also be caused by an out of adjustment, or bad TPS.

Depends on the system of course, but a bad TPS can also raise havoc on starting, and can either cause a cold starting problem, or a hot starting problem. Depends on what happens when it fails.

Have you tried holding the accelerator to the floor before trying to start the engine? Some EFI systems shut the fuel off at WOT so the engine can be cleared if it does become flooded.
I had a similar issue with the '99 Suburban, and it turned out that not only was the TPS bad, but half of the injectors were leaking as well. If you have the same cheap plastic injectors that the Suburban uses, you may want to check them.
Also, I'm not real sure about this, but I kinda remember something about the FPR being under the intake, and was part of the injector assembly. Then again, maybe it was part of the fuel pump assembly? lol...Sorry, too many years, and way too many cars.
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Old 12-18-2011, 09:39 PM   #58
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The engine I have has no FPR, it'* a single fuel line.
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Old 12-18-2011, 11:58 PM   #59
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The engine I have has no FPR, it'* a single fuel line.
Understood. But... this in itself does not mean there is no regulator in the system.

There must be a regulator in the system at some point, because if there wasn't, the pressure would be unstable, and would be whatever pressure the pump was putting out. This would just not work very well.
Either the pump has a regulator build into it, (has a some type of relief valve that lets fuel return into the fuel supply, etc.) or there is a regulator located down stream of the pump. Not all EFI systems have return lines, but as best as I can recall, they all have regulated line pressure.
Since the regulator can not be purchased as a separate part, I'd suspect that it is part of the pump.

The line pressure can not be the same as the pump pressure, if you know what I mean.

A line pressure test is kind of limiting, in that, it may show that the pressure is low, or that the system isn't holding the line pressure as long as required after the pump has been shut down, but it will not tell what the cause of the problem is. Low pressure can be a weak pump, or the regulator. Leak down can be caused by a number of things.

If it starts cold, why do you suspect the fuel system? Seems that it would have more problems starting when it was cold if the fuel system was at fault. Unless it was flooding, or vapor locking when it was hot. And since EFI isn't suppose to vapor lock, it kind of narrows it down. Just saying....Its just something else to consider.
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Old 12-19-2011, 07:29 AM   #60
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fyi, the 96-99 trucks and vans are the only ones that had those stupid spider injectors, and there is a electronic injector upgrade kit so they dont leak like that.
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