Guru's of the IAC, TPS, CPS, etc.....

[olyelr]

OK fellas, I have searched and read a zillion threads about this, but found no "for sure" answers with my issue. If my truck sits for a while (2-3 days typically), when I first start it it will instantly stall unless I have steady throttle pressure. It only seams to do this after sitting for a while, then after a minute or less its good to go for several days until it sits again. From researching, it sounds like it could be possibly one of several of the sensors, none of which I know anything about. Any ideas for which one it might be? And how exactly do you "test" a sensor? Any suggestions would be great. Its no real issue yet... all I have to do is keep my foot on the gas when I first start it. But, I know its not right and I don't want any further issues to occur. Thanks in advance for any recommendations fellas

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[kev2]

letting it sit a few days.....does it crank more before starting? thinkling fuel press leakdown....
hopefully no CEL?

[Hammer Down]

+1 on the fuel pressure leak. I've seen this happen on a Toyota T100 once before.

[dhvaughan]

you could check the fuel pressure with a gauge to rule it out. should be about 49.

i'm thinking weak battery. its plays hell with the reference voltage that those sensors use. you could rule it out by charging the battery some during your 3 day down time.

[olyelr]

Fuel pressure. Hmmm, that never came up in any of my searching.


Yeah, fires right up like always on the first crank, but then instantly dies. Then it wont do it for again until it sits for a while, even if its a week or two later.

That would explain why it only does it after a long sitting (as apposed to a sensor which would most likely do it all the time, correct?).

Also, I disconnected the main fuel line last time I did the plenum, timing chain and water pump. Maybe it didn't get a good seal when I reinstalled it?

Guess I will have to check up on the fuel pressure deal, problem is I don't know how. Any quick how-to's?



And thanks for the quick reply's guy's!

[Ram15002ndGen]

To test fuel pressure, your year should have a connector on the fuel rail.

You may also want to check your IAC since that controls the air at start up when the truck is cold. See if it's all gunked up.

[Twisted Metal]

+1 on the IAC check/clean. Haynes or Chiltons both have test porcedures for the sensors using a multimeter. I am with Vaughn on battery voltage, while you have the multimeter out, check the battery.

[speeddemon31176]

There is a valve on the fuel rail called a schraeder valve. It looks just like a short valve stem for your tires. You need a fuel injection pressure tester, which is available at any parts store for a reasonable price. You follow the installation instruction that come with the tester which is usually to screw it onto the schraeder valve. then start the truck and watch the gauge on the tester. It should be at about 50lbs. at idle and then take your handle and move the throttle and watch the gauge. It should increase steadily with the throttle indicating that the pressure regulator is good as well. that is about as short as I can make it for you. Hope this helps. You should also look into cleaning the IAC orifice and the IAC itself, if not even replace the IAC if it doesn't pass the test with a multimeter.

[olyelr]

Oh yeah, the battery. Suppose I will check that too while I'm messing around. It was brand new lass than a few years back, but I suppose that does not mean a thing. I replaced the factory battery after over 8 years of use, and the dang thing was still working great... I just figured it would be good maintenance. It would make sense the new one would be weak already



Thanks on all the quick replies fellas. I will start investigating today after work and let you guys know what I find out.

[Sheriff420]

advance has a fuel pressure test kit for about 150$ and it is a loan a tool so you will only be out the 150 until you return it.