Bogging down
Thread Starter
Teching In
Joined: Apr 2012
Posts: 9
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From: Austin, TX (Afghanistan)
Bogging down Hello all,
With the knowledge on this forum I put an 02 5.3 in my 88 Jimmy. It starts and runs but bogs down just past half throttle. I've cleaned the MAF, TB, IAC, seafoamed it, and replaced the O2 sensors (rears have been programmed off). Fuel pump (delfi for a '96 3500) and filter are new. Just wondering if anyone had any ideas.
With the knowledge on this forum I put an 02 5.3 in my 88 Jimmy. It starts and runs but bogs down just past half throttle. I've cleaned the MAF, TB, IAC, seafoamed it, and replaced the O2 sensors (rears have been programmed off). Fuel pump (delfi for a '96 3500) and filter are new. Just wondering if anyone had any ideas.
Thread Starter
Teching In
Joined: Apr 2012
Posts: 9
Likes: 0
From: Austin, TX (Afghanistan)
Thread Starter
Teching In
Joined: Apr 2012
Posts: 9
Likes: 0
From: Austin, TX (Afghanistan)
Well, I got a fuel pressure test kit from Harbor Freight. I hooked it up to the valve on the rail and at idle it reads around 10-11 psi and when I give it throttle up to half it drops down to 8 psi right before it bogs. I guess it's a weak or incorrect fuel pump causing it to bog? From what I've found the EP381 is the way to go.
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Thread Starter
Teching In
Joined: Apr 2012
Posts: 9
Likes: 0
From: Austin, TX (Afghanistan)
Got another tester and it reads 12 psi at idle. It will run a little better with the MAF unplugged up over 1/4 throttle, with it plugged in it starts bogging past idle and dies most of the time. Going to get another MAF, already cleaned the one on it. Could anything else cause the low fuel pressure besides the pump?
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Verdad Gallardo Thread Starter
Teching In
Joined: Apr 2012
Posts: 9
Likes: 0
From: Austin, TX (Afghanistan)
I clamped the return line shut, raised it to around 14-15 psi. There are no leaks in the lines. I'm leaning towards the fuel pump. I'm going to get a Delco this time. I installed it on the stock sending unit (88 K5 5.7 TBI), is this okay or should I have done something different?
I wouldn't think sender to be a problem... do you have the ability to do a dead head pressure test at the fuel filter before everything goes to the rail? that's always the next check I do... then if its still low check the filter, if filter is good then id look at fuel pump... sometimes the hose between the pump and the sending unit splits. especially if you used the wrong type of hose.. has to be fuel injection grade.
Thread Starter
Teching In
Joined: Apr 2012
Posts: 9
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From: Austin, TX (Afghanistan)
One of the first things I did was put another new filter on it. When I wired the harness I checked that it was pushing 12v all the way to the pump but I'll recheck it and the ground. I just bought a tester that connects to the valve on the rail. I used the hose and clamps that came with the pump. I'm going to drop the tank and check it out. Will probably just change the pump out.
another thought... are you actually using the 5.3 fuel rail with the regulator and the return line..... if so try to block off or pinch off the return line and see if the pressure builds could be the regulator dumping fuel pressure... very quick check is take the vac hose off and see if fuel dribbles or sprays out.. if it does replace and retest.