Runs rough when hot.
Senior User
Joined: Jan 2003
Posts: 217
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From: Saraland AL
Runs rough when hot.
I've had very similar problems in two different vehicles.
First was my truck- It was a contaminated fuel problem. I had bought gas at a station out of town and picked up water in the fuel. Put in some fuel system treatment and it eventually ran out. Not sure why it didn't show up at low rpm.
Pour the contents of your fuel filter into a clear jar and look at what comes out. If it's good, bad fuel won't be the problem.
Also had high rpm trouble in my Honda CRX. That was a booger to figure out. Turns out it was the distributor rotor. It didn't fit as snug as it was supposed to and would retard the timing at hiway rpm. It was a problem with the brand, a different brand fit very well and performed great.
First was my truck- It was a contaminated fuel problem. I had bought gas at a station out of town and picked up water in the fuel. Put in some fuel system treatment and it eventually ran out. Not sure why it didn't show up at low rpm.
Pour the contents of your fuel filter into a clear jar and look at what comes out. If it's good, bad fuel won't be the problem.
Also had high rpm trouble in my Honda CRX. That was a booger to figure out. Turns out it was the distributor rotor. It didn't fit as snug as it was supposed to and would retard the timing at hiway rpm. It was a problem with the brand, a different brand fit very well and performed great.
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Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
Runs rough when hot.
I took the truck to a 'Cruise Night' sponsored by my Rod Club last Saturday evening. It was only a few miles away, but I had no problems either way. I am going to have to take it for a longer ride. I am a bit gun shy. I don't want to go a long distance and find out that it's not fixed, but if I don't try I'll never know.
It is like trying to prove a negative. If it doesn't happen, is it fixed or is it not tested enough.
It is like trying to prove a negative. If it doesn't happen, is it fixed or is it not tested enough.
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Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
Runs rough when hot.
It wqs a beautiful summer day today. The temperature was in the low 80's and the sun was shining. I had some errands to run, so I took the truck. I went to the bank, the Post Office, took some drain motor oil to the Auto Store for recycling and went to the hardware store for some tools that I need for a home project.
The truck ran great the whole trip. The water temp was 190 degrees maximum. I was in stop and go traffic most of the time, only getting up to cruising speed on the last couple of miles home.
Tomorrow it is supposed to reach about 90 degrees, I may try another trip. This problem previously occurred in hot weather and disappear in cooler weather. I have to cure it now when the days are hot or I'll never be sure.
I think that it is a combination of thin hot air, richer mixture, low intake velocity, low intake temperature, and cold plug heat range. The only things that are readily changeable in that list are intake manifold temperature and plug heat range. These are what I have changed. I don't want to tinker with the mixture, because it runs so good when cold.
The truck ran great the whole trip. The water temp was 190 degrees maximum. I was in stop and go traffic most of the time, only getting up to cruising speed on the last couple of miles home.
Tomorrow it is supposed to reach about 90 degrees, I may try another trip. This problem previously occurred in hot weather and disappear in cooler weather. I have to cure it now when the days are hot or I'll never be sure.
I think that it is a combination of thin hot air, richer mixture, low intake velocity, low intake temperature, and cold plug heat range. The only things that are readily changeable in that list are intake manifold temperature and plug heat range. These are what I have changed. I don't want to tinker with the mixture, because it runs so good when cold.
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