400- 4 missing cylinders
Thread Starter
|
New User
Joined: Aug 2003
Posts: 9
Likes: 0
400- 4 missing cylinders
'77 F-250 400 4x4
I seem to have four missing cylinders on my pickup. 2,3,5,&8. I could use some help diagnosing this problem. All cylinders range in compression from 110(lowest) to 140(highest) with a 125 average psi. (the dead cylinders seem to be higher, possibly from carbon buildup?) All have new spark plugs with a good spark to them(checked with tester, very good spark on all cylinders). All this on a supposed "fresh rebuild". I did not rebuild it myself and did not know who did, neither did the person who sold it to me. Ran great when I got it. Not sure whats going on, any help would be GREATLY appreciated.... Ken
I seem to have four missing cylinders on my pickup. 2,3,5,&8. I could use some help diagnosing this problem. All cylinders range in compression from 110(lowest) to 140(highest) with a 125 average psi. (the dead cylinders seem to be higher, possibly from carbon buildup?) All have new spark plugs with a good spark to them(checked with tester, very good spark on all cylinders). All this on a supposed "fresh rebuild". I did not rebuild it myself and did not know who did, neither did the person who sold it to me. Ran great when I got it. Not sure whats going on, any help would be GREATLY appreciated.... Ken
Posting Guru
Joined: Aug 2002
Posts: 1,214
Likes: 2
From: Minneapolis, MN
400- 4 missing cylinders
Inner two (2 & 3) cylinders on one bank and outer two (5 & 8) cylinders on the other bank all run on one side of the carb on a dual plane manifold. Either one of the main jet is plugged in the carb or there's a major vacuum leak on the side that feeds those cylinders.
Thread
Thread Starter
Forum
Replies
Last Post
StarTrash
1973 - 1979 F-100 & Larger F-Series Trucks
23
Jun 25, 2024 04:00 PM
dubbs2012
1983 - 2012 Ranger & B-Series
4
Oct 16, 2012 05:57 PM
