Engine trouble
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Senior User
Joined: Jun 2004
Posts: 154
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From: San Antonio
Engine trouble
Recentley (1400mile) had my engine rebulit. I am having this problem where the engine is in high idle. when you turn off the truck and re start it it usually brings it back down to 600rpm or so. I have this jumper wire between my fuel pump relay and the eec relay. I dont know why its there, but the truck wont run with out it pluged in. can anyone help me solve this problem.
302 rebulit has only 1400 mile on it,
tranny rebuilt has about twice that.
302 rebulit has only 1400 mile on it,
tranny rebuilt has about twice that.
Postmaster
Joined: Jun 2001
Posts: 2,809
Likes: 3
From: Loveland, CO.
Is your truck EFI? If so, the idle problem is most likely the IAC, and if not, the TPS. I have found that the IAC is the problem more frequently than the TPS is, because the IAC gets dirty and doesn't work right as opposed to the TPS which isn't affected by dirt and fails only when it is physically broken somehow. Sometimes you can take the IAC apart and clean it and that will solve your problem. It's easy enough to do, it comes off in 5 minutes. Also clean the TB while you are there.
As far as the jumper wire, I am not sure about why it is there but it sounds like somebody bypassed a wire that was broken somewhere within the harness. I am guessing that the wire gives juice to the fuel pump relay, which is why it won't run without it. As long as the jumper wire is properly placed (ie. it covers the same exact circuit that it replaced and is the right size wire) then there is nothing wrong with it. I've got one on my truck as well, I had a hot lead go bad inside one of the connectors on the firewall harness - I wasn't going to rewire a whole new harness connector for that. I simply jumped that one wire around the harness connector.
As far as the jumper wire, I am not sure about why it is there but it sounds like somebody bypassed a wire that was broken somewhere within the harness. I am guessing that the wire gives juice to the fuel pump relay, which is why it won't run without it. As long as the jumper wire is properly placed (ie. it covers the same exact circuit that it replaced and is the right size wire) then there is nothing wrong with it. I've got one on my truck as well, I had a hot lead go bad inside one of the connectors on the firewall harness - I wasn't going to rewire a whole new harness connector for that. I simply jumped that one wire around the harness connector.
Thanks
Postmaster
Joined: Jun 2001
Posts: 2,809
Likes: 3
From: Loveland, CO.
The IAC is mounted on the throttle body, on the right side as you look at the truck from the front. It has two screws that hold it on. It's basically underneath the plastic "hat" that is on top of the TB. I don't have a picture of one but I think that someone posted a pic of one here. Try searching for that thread, or if anybody here has that pic can you post it? To clean the IAC and the throttle body, you can purchase a spray at any auto parts store. Just be sure that it is labelled for throttle bodies and not just carburetors. Old fashioned carb cleaners can destroy the seals in the throttle body.
If you take the IAC off, be sure to have a gasket ready for when you put it back on.
If you take the IAC off, be sure to have a gasket ready for when you put it back on.
Last edited by JBronco; Mar 7, 2005 at 05:51 PM.
Postmaster
Joined: Jun 2001
Posts: 2,809
Likes: 3
From: Loveland, CO.
I found it.
https://www.ford-trucks.com/user_gal...oid=70123&.jpg
When I did mine I removed the large intake hoses from the TB and also the plastic "hat." It made it a lot easier to work on, and you need to take off the intake hoses anyway to clean the TB. You can clean it on the truck like I have been doing, but if it is very dirty then you might want to remove the TB so you can clean it real well. Mine has never been very dirty (I attribute this to using a factory air filter sealed in its box instead of a high flow) so I can clean it on the truck. I'm not positive about my air filter theory, but for whatever reason, the TB has always been very clean.
https://www.ford-trucks.com/user_gal...oid=70123&.jpg
When I did mine I removed the large intake hoses from the TB and also the plastic "hat." It made it a lot easier to work on, and you need to take off the intake hoses anyway to clean the TB. You can clean it on the truck like I have been doing, but if it is very dirty then you might want to remove the TB so you can clean it real well. Mine has never been very dirty (I attribute this to using a factory air filter sealed in its box instead of a high flow) so I can clean it on the truck. I'm not positive about my air filter theory, but for whatever reason, the TB has always been very clean.
Last edited by JBronco; Mar 7, 2005 at 05:59 PM.
