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Compression test, pull fuel relay?

1987 - 1996 F150 & Larger F-Series Trucks 1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks

Compression test, pull fuel relay?

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Old

May 10, 2016 | 09:11 PM

#1

Dean06919

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Tuned

Joined: Aug 2014

Posts: 305

Likes: 2

Compression test, pull fuel relay?

If I have time, I'd like to do a compression test on my 1994 and 1996 F350's (351 and 460). If I remember correctly, the fuel relay is under the hood, by the drivers side, right? Also, do I need to pull it, I seem to remember that when the throttle is wide open, the computer shuts off fuel anyway. Is that correct?

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Old

May 11, 2016 | 08:42 AM

#2

Phy

Fleet Mechanic

Joined: Jan 2011

Posts: 1,709

Likes: 4

From: 8600 ft in Colo

If you leave the key off, and jump the starter relay to turn the engine, you don't have to worry about it.

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Old

May 11, 2016 | 10:00 AM

#3

Da_Lariat_Chariot

Laughing Gas

Joined: Feb 2015

Posts: 765

Likes: 1

Quote:

Originally Posted by Dean06919

If I have time, I'd like to do a compression test on my 1994 and 1996 F350's (351 and 460). If I remember correctly, the fuel relay is under the hood, by the drivers side, right? Also, do I need to pull it, I seem to remember that when the throttle is wide open, the computer shuts off fuel anyway. Is that correct?

It's in the same block as the DLC connector and trailer tow relay (if equipped). Right behind the air filter box and PCV breather tube. Yes, you can pull that and that will kill both fuel pumps for your test. Remove spark plugs and block throttle wide open, crank each time for ~3 seconds. As long as the lowest reading is at least 75% of the highest reading generally you're ok.

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Old

May 11, 2016 | 01:11 PM

#4

sgip2000

Mountain Pass

Joined: Mar 2015

Posts: 200

Likes: 1

From: Hillsboro, OR

You can disconnect the coil too.

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