Odd occasional startup
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From: Central Ohio
Odd occasional startup
'97 4.2L 188K miles bone stock. Every week or two, winter or summer, on a cold startup first thing in the morning, I will start the truck and it will run VERY rough. Worse than a 2 or 3 cylinder misfire. If I let it run, it will work its way out of it in 2 to 10 seconds, the IAC will have worked out to hold up the idle so there is a big flare in idle RPM but it comes right back down. Alternatively, if I immediately turn it off, and immediately start it again, it is always perfect. Truck has always run just fine except for a couple of these per month. It has been this way for 8 years, no change as it ages.
It isn't the IAC because it is retracting to hold the idle speed up, the flare verifies this. I don't suspect a fueling or secondary problem or I would have one at other times. Does the CKP or CMP ever mistime on startup on these engines? That's kind of what it feels like. Ideas?
Thanks
It isn't the IAC because it is retracting to hold the idle speed up, the flare verifies this. I don't suspect a fueling or secondary problem or I would have one at other times. Does the CKP or CMP ever mistime on startup on these engines? That's kind of what it feels like. Ideas?
Thanks
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From: Central Ohio
No, it starts on one revolution or less, it just starts all jumbled up. And it happens so infrequently that I never check for fuel pump noise on startup (my pump is quiet, I can't hear it in the truck). I may pull the fuel pump relay before starting it one day (if we ever have pleasant weather) and see if it acts the same way. If it is a fuel pump issue, it'd have to be the relay or wiring because I get good rich O2's on WOT. I've done that (have a little OTC Visor scanner that's handy in the cab) a couple of times just because you'd think after 180K miles, the fuel filter would plug some day. Just not yet.
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From: Louisville,Ky.
My 96 Windstar does this too. Sometimes it has to crank a bit before starting. I have noticed that when I check the fuel pressure, it holds pressure if I turn the key on and it goes up to about 40psi, then turn the key off. The when running it idles about 32psi, but immediately drops to 0 when I turn it off. I am wondering if it us a regulator problem even though it works fine when running 32psi idleing, 40 psi when vacuum is removed from it and no fuel is in the vacuum line. It runs great when the sometime start-up miss goes away. I never has thrown a code. I am going to try to catch it acting up and look at the real-time data on my new Diablosport programmer to see if anything looks odd.
The IAC is good and the MAF is clean. About 15,000 miles on plugs, wires and coil-pack. Did it before and after the tune-up. Fuel filter was replaced 2 oil changes ago.
The IAC is good and the MAF is clean. About 15,000 miles on plugs, wires and coil-pack. Did it before and after the tune-up. Fuel filter was replaced 2 oil changes ago.
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From: Central Ohio
LxMan1, Be sure to share if you figure it out. Seems a lot of GM fuel systems don't hold pressure either. Pinch off the return line behind the regulator and they still don't hold pressure. Seems to go back through the check valve. Most start up fine, some crank a couple of revolutions but very few complaints. According to diagnostic flowcharts they should be replaced but they aren't causing any problems.
The 8psi drop is around a little less drop than I would have expected but even if it ran a little rich at idle, it should run fine after the O2s warm up. I wouldn't worry about the regulator based on that.
Is yours just extended cranking? If it is and it's regular, just do what racerguy suggested. Either key on, wait 2 seconds, then crank or better turn the key to run for 2 seconds, the off, then back on for 2 more before cranking. If that fixes it, it is probably the check valve which I expect is in the fuel pump assembly. I'd hate to drop my tank or pull my bed just for that.
Does it ever start all jumbled up? Or just the extended crank?
The 8psi drop is around a little less drop than I would have expected but even if it ran a little rich at idle, it should run fine after the O2s warm up. I wouldn't worry about the regulator based on that.
Is yours just extended cranking? If it is and it's regular, just do what racerguy suggested. Either key on, wait 2 seconds, then crank or better turn the key to run for 2 seconds, the off, then back on for 2 more before cranking. If that fixes it, it is probably the check valve which I expect is in the fuel pump assembly. I'd hate to drop my tank or pull my bed just for that.
Does it ever start all jumbled up? Or just the extended crank?
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From: Central Ohio
You know, after all these years, I've never looked at AllData for a TSB. There was one on Dec 9, 1997. Correction is replace spark plugs and reflash the PCM with newer calibration. This sounds a lot like me. My truck was built in August of '96, one of the very first ones.
PCM - Hard Start/Misfire/Stall/MIL ON/DTCs Present
Article No. 97-12-9 06/09/97
^ HARD START - AT ALL AMBIENT
TEMPERATURES - VEHICLES WITH 4.2L ENGINE
^ STALL - ROUGH IDLE - HESITATION/STUMBLE -
AFTER COLD START - AT ALL AMBIENT
TEMPERATURES - VEHICLES WITH 4.2L ENGINE
LIGHT TRUCK: 1997 E-150, F-150
I removed some symptoms from the list, most had to do with MIL and misfire codes. Never got any of them surprisingly, but all stressed NO DRIVEABILITY CONCERNS PRESENT. Just like mine. Unfortunately, the .9 hours and spark plugs were only free for the emissions warranty period. Hmmm, probably don't qualify.
PCM - Hard Start/Misfire/Stall/MIL ON/DTCs Present
Article No. 97-12-9 06/09/97
^ HARD START - AT ALL AMBIENT
TEMPERATURES - VEHICLES WITH 4.2L ENGINE
^ STALL - ROUGH IDLE - HESITATION/STUMBLE -
AFTER COLD START - AT ALL AMBIENT
TEMPERATURES - VEHICLES WITH 4.2L ENGINE
LIGHT TRUCK: 1997 E-150, F-150
I removed some symptoms from the list, most had to do with MIL and misfire codes. Never got any of them surprisingly, but all stressed NO DRIVEABILITY CONCERNS PRESENT. Just like mine. Unfortunately, the .9 hours and spark plugs were only free for the emissions warranty period. Hmmm, probably don't qualify.
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From: Syracuse
I had a '98 company truck with a 4.2, It acted as you describe after a long haul on the highway. When I got off the highway and stopped, it would barely stay running. If I slipped it into neutral, and goosed it a couple times, it usually cleared up. I worked for a dealer, (it was their truck) and brought it in several times with no answer. Even when it was acting up, they couldn't figure it out, and these guys were the best around. Finally they determined it was me!!! Rob
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From: Central Ohio
D**n, the cobbler's wife goes barefoot for sure. My two most annoying problems with this truck are a whine in the AM radio, TSB for RFI filter in fuel pump line, and an extremely grabby right rear brake on first application when humid or raining, new style brake shoe. It grabs so bad, it will sometimes kill the engine. After a few seconds use it is fine. I look at TSBs all the time but never looked up my own d**n truck.
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From: Central Ohio
LxMan1, if the check valve was absolutely toast, that is the pressure fell back to zero immediaitely, running the pump a couple of times wouldn't help. That is if the pump ran a second, then stopped and the pressure fell entirely away in a second, then repeat, it wouldn't help. The GM filters fall off in a minute or two, not immediately. I'm just guessing here. How fast does the pressure drop?
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From: Central Ohio
I can't explain that at all. I'd let it run, pinch off the fuel return after the fuel pressure regulator, cut it off (quickly) and see if the pressure fell off rapidly. If it didn't, I'd say the FPR is shot. If not, I'd pinch off the supply line before the rail and quickly cut it off. If pressure didn't fall off then, I'd say it was the check valve. If pressure fell off quickly in both cases, I'd pinch them both off and if pressure still fell right off you'd have either a dripping injector or a ruptured diaphram in the FPR or a leaky rail.
But that begs the question of the long crank. If you can hit the pump a few times with the key, the pressure bleed off is slow, it should still fire right up. Could it be you have two problems? One is pressure bleeds but that's not the cause of the long crank. Then some other long crank problem?
But that begs the question of the long crank. If you can hit the pump a few times with the key, the pressure bleed off is slow, it should still fire right up. Could it be you have two problems? One is pressure bleeds but that's not the cause of the long crank. Then some other long crank problem?
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