Unique fuel problem.
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Joined: Jan 2002
Posts: 17
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From: Coeur d' Alene USA
Unique fuel problem.
I have 2 70's trucks, one with a 360 and one with a 390. Which I don't think makes any difference. The problem is, I experienced poor operation in that after driving for a while engine showed symptoms of reduced performance and stalling and shortly stalling all together. It would not restart even after changing fuel filters and checking pressure. It has a two barrel holley. I took the top off the carb to check for debris in the jets. What I found was a clear jelly like substance. I pulled it out and set it in the open air. After a few minutes it evaporated. I concluded it was something like alcohol created by the vacuum in the carb. After that the truck ran fine until it happened again a few days later. Always after sitting it would restart. When it did not I found the substance in the carb. Now I have the same problem with the other truck. It sounds like a few of the cylinders are starving for fuel and the carb is all but new with twin fuel filters. Ignition is fine on both trucks after hooking up the scope. What is this crap and how to get rid of it?
Moderator
Joined: Aug 2002
Posts: 6,104
Likes: 384
From: Southern California
IMHO, it's varnish......that is what happens when these new blended fuels sit for about 6 months..............I would clean the carbs real good, personally, I use marvel mystery oil to help keep this from happening.......acetone (about 1/2 pint for a 16 gallon tank) or methanol (10% max) is also very good for cleaning out the system
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Ethanol doesn't help (phase separation) but fuels start to gel, clear at first as it starts to oxidize and eventually will turn to tar *****. Always use fresh fuel and keep truck out of direct sunlight if possible, tank topped off, use a stabilizer helps some etc.
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