Hard start when warm
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Posting Guru
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From: Panama City, Fl
Hard start when warm
Yep....did the search.....this is a fail to fire issue, not a cranking issue.
My '93 5.0, 101,000 miles has a small issue. It has been hard to start when warm since buying it a couple weeks ago. Cycling the key on and off 3-4 times helped so we thought the fuel pressure regulator was the problem. Truck had a very slight surge when cruising on level ground. Had a slight gas odor from the vac. line.
Changed the regulator....still starts hard when warm but now has an erratic idle and roughness to the idle. Truck has new wires, plugs and such. No gas smell at vac. line now. The truck gets right up to 70+ with no issues until settling into a cruise.
Check engine is lit and has been...just borrowed a scanner so will hit that tomorrow am.
Fuel pump sounds good. I am thinking a fuel filter.....no idea of its age. Is there anything associated with going over 100,000 miles that would trip the engine light?
My '93 5.0, 101,000 miles has a small issue. It has been hard to start when warm since buying it a couple weeks ago. Cycling the key on and off 3-4 times helped so we thought the fuel pressure regulator was the problem. Truck had a very slight surge when cruising on level ground. Had a slight gas odor from the vac. line.
Changed the regulator....still starts hard when warm but now has an erratic idle and roughness to the idle. Truck has new wires, plugs and such. No gas smell at vac. line now. The truck gets right up to 70+ with no issues until settling into a cruise.
Check engine is lit and has been...just borrowed a scanner so will hit that tomorrow am.
Fuel pump sounds good. I am thinking a fuel filter.....no idea of its age. Is there anything associated with going over 100,000 miles that would trip the engine light?
Lead Driver
Joined: Sep 2002
Posts: 9,182
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From: Gateway to the West
Research the ECT sensor. I'll put dollars to doughnuts its your culprit. Read this thread or search "ECT sensor hard start"
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Posting Guru
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From: Panama City, Fl
Well.....went out and did the scanner testing. Got codes 126, 173, and 332. Read up on them and thinking I need a few sensors. Hmmmmm. Get in truck to move it and the a/c stays in defrost which it never did before.
I know that issue...vacuum leak. So, I start chasing vacuum lines.....right on top of the intake, there is a hose floating free and I see a dirty (fresh grease) connection on the intake. Cleaned the grease of and reconnected the line. A/C now switches properly and I bet the other three codes may disappear......
So, truck starts a bit better but still has some issue when warm, and idles fine. Will do another scanner when I relax from wanting to strangle the mechanic who did the pressure reg. Just a carelessly placed hand for support and not checking things. Hate taking it to shops but with a bad back, the fuel pressure regulator is a real problem to work on......
And, I will stop by the shop soon......
I know that issue...vacuum leak. So, I start chasing vacuum lines.....right on top of the intake, there is a hose floating free and I see a dirty (fresh grease) connection on the intake. Cleaned the grease of and reconnected the line. A/C now switches properly and I bet the other three codes may disappear......
So, truck starts a bit better but still has some issue when warm, and idles fine. Will do another scanner when I relax from wanting to strangle the mechanic who did the pressure reg. Just a carelessly placed hand for support and not checking things. Hate taking it to shops but with a bad back, the fuel pressure regulator is a real problem to work on......
And, I will stop by the shop soon......
Lead Driver
Joined: Sep 2002
Posts: 9,182
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From: Gateway to the West
Put in in the oven with your ohm meter attached to it. (Suggest leaving the meter OUTSIDE the oven... I know, I know but if I actually SAY it, maybe we won't be fielding complaints about people melting down their test equipment.) I've posted the resistance value chart for both the ECT and ACT sensors (the numbers are nearly identical for both sensors) in several other threads for people with the same issues.
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From: Panama City, Fl
Did a cold test of the ECT while in the truck. It has right at 5 volts supplied which I find is correct. The ohms test showed complete open. No reading at all. Ran out of time to do the hot testing.
Being open when cold should tell the computer it is cold....correct?
Experimented a bit today when hot starting....flooring the pedal made no difference in warm starts. It does start quick with q min. of three cycles of the key for the furl pump to run.
That thing looks like a pain to remove too....lol If I remove it for testing, I may just as well install a new one.....but still test the old.
Also cannot break lose the exhaust tube from the EGR so......more time to soak might help.......
Some reading stated the ECT would throw codes .....somewhere in the 50 - 60 range of codes but never actually had the time to look them up.
Being open when cold should tell the computer it is cold....correct?
Experimented a bit today when hot starting....flooring the pedal made no difference in warm starts. It does start quick with q min. of three cycles of the key for the furl pump to run.
That thing looks like a pain to remove too....lol If I remove it for testing, I may just as well install a new one.....but still test the old.
Also cannot break lose the exhaust tube from the EGR so......more time to soak might help.......
Some reading stated the ECT would throw codes .....somewhere in the 50 - 60 range of codes but never actually had the time to look them up.
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Lead Driver
Joined: Sep 2002
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From: Gateway to the West
Dead open... so no resistance at all?! Replace it. At dead cold the resistance should be nearly 60,000 ohms! This is why it won't start. Read the explanation HERE.
Yes, ALL of the sensors are fed +5VDC (except the O2 sensor) and the ECM uses the altered voltage coming BACK to it to determine what is going on and make adjustments.
Yes, ALL of the sensors are fed +5VDC (except the O2 sensor) and the ECM uses the altered voltage coming BACK to it to determine what is going on and make adjustments.
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Posting Guru
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From: Panama City, Fl
I have read everything I have seen on this problem.
Yes, my meter had absolutely no reading. Meter works on other items. Plan on testing again today to double check things.
With it having no resistance at all....it still starts great when cold.....and starts when warm after three key on/off cycles.
I do plan on a replacement soon.....
Yes, my meter had absolutely no reading. Meter works on other items. Plan on testing again today to double check things.
With it having no resistance at all....it still starts great when cold.....and starts when warm after three key on/off cycles.
I do plan on a replacement soon.....
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From: Panama City, Fl
Tested again......I felt I was not getting a good connection yesterday. I was right.
At 82* outside temp.....31,200....after engine warm up.....3200....so it appears that it is functioning good.
Bad EGR should not cause hard starts when warm would it? I have not seen that before.
At 82* outside temp.....31,200....after engine warm up.....3200....so it appears that it is functioning good.
Bad EGR should not cause hard starts when warm would it? I have not seen that before.
Lead Driver
Joined: Sep 2002
Posts: 9,182
Likes: 12
From: Gateway to the West
Unless the valve is stuck and the closed and the ECM thinks its open. Then there is less air in the combustion cycle than the fuel/air ratio the system is running. The inverse problem would be true as well.
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