Chug & Jerk?
Thread Starter
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Freshman User
Joined: Dec 2006
Posts: 29
Likes: 0
From: Knoxville Tn.
Chug & Jerk?
Howdy All, got a 87 F150, 4x4, 4.9 inline 6, 4 speed all stock.
I got a chug, jerk in the truck, starting out in 2nd, chug, jerk
in 3rd, but not in 4th. Only does it 1 out of 6 times, and only
when I have it on the front tank. Doesn't do it on the back
tank. Could my front tank fuel pump be going out? or something
else, I put in new fuel filter, plugs, wires, cap, and coil, timing
is right. Thanks!
I got a chug, jerk in the truck, starting out in 2nd, chug, jerk
in 3rd, but not in 4th. Only does it 1 out of 6 times, and only
when I have it on the front tank. Doesn't do it on the back
tank. Could my front tank fuel pump be going out? or something
else, I put in new fuel filter, plugs, wires, cap, and coil, timing
is right. Thanks!
Elder User
Joined: Feb 2006
Posts: 537
Likes: 1
From: Formerly Nawlins
Check your fuel pressure from both tanks ... my guess is your front is not supplying enough pressure at idle. Mine is a 90 with a different fuel system than yours, but I have a low fuel pressure problem from the front tank too, and I just replaced the pump .... it had the problem with the old pump but also a crossflow problem as well.
Mine runs okay on the highway on the front ... get 45PSI, rear gives 49PSI. Front goes down to 30PSI at idle on mine and that is what gives me what you are seeing ... but mine really is only bad at a stoplight. Does yours die at a long stoplight if you let it sit at idle?
Mine runs okay on the highway on the front ... get 45PSI, rear gives 49PSI. Front goes down to 30PSI at idle on mine and that is what gives me what you are seeing ... but mine really is only bad at a stoplight. Does yours die at a long stoplight if you let it sit at idle?
Thread Starter
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Freshman User
Joined: Dec 2006
Posts: 29
Likes: 0
From: Knoxville Tn.
No! mine doesn't die at stoplights. It will idle all day long, and not die. It idles fine.
It runs great on highway, It just chug's & jerks once in awhile, when I pull out from
a stop. After I hit 4th gear, it don't do it. I have a low pressure fuel pump in both
front & rear tanks, and a high pressure pump on the frame. It only does the chug &
jerk on the front tank, so the primary high pressure pump is working fine, because it
works the rear tank fine.
It runs great on highway, It just chug's & jerks once in awhile, when I pull out from
a stop. After I hit 4th gear, it don't do it. I have a low pressure fuel pump in both
front & rear tanks, and a high pressure pump on the frame. It only does the chug &
jerk on the front tank, so the primary high pressure pump is working fine, because it
works the rear tank fine.
Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
It's odd that it only does it on the front tank. I can't see how it would be fuel pressure related because they share the same high pressure pump. I think the only way to rule it out is to put a fuel pressure gauge on it. You can pick one up at sears or a parts store for about $30.
Also, have you pulled the codes?
Also, have you pulled the codes?
Thread Starter
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Freshman User
Joined: Dec 2006
Posts: 29
Likes: 0
From: Knoxville Tn.
Yap! pulled codes and no codes present. My fuel pressure is about 50 psi, but like
I said, the idle is right and it only does it once in awhile. I was thinking maybe the
low pressure pump in the front tank maybe going out. It's kind of hard to pin point,
when it only does it, coming out of a stop. Thanks guys
I said, the idle is right and it only does it once in awhile. I was thinking maybe the
low pressure pump in the front tank maybe going out. It's kind of hard to pin point,
when it only does it, coming out of a stop. Thanks guys
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