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Motor Bogging and Coughing after splicing fuel line

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Hi, I recently had a fuel leak at my quick connect fuel line, so I cut the line, removed the quick connect piece, and spliced in some new 5/16" fuel line and clamped it down.


Right after doing that the truck started coughing and bogging down. When it does that, I put it in neutral, rev it, and put it in drive again to get it moving. Ten to twenty seconds later, it does it again. It seems to get worse the warmer the motor gets, but still doesn't take long for it to start coughing.


- could there be air in the fuel line? not enough pressure?


- do the quick connect pieces have a backflow prevention that is now missing?


Any ideas?


Many thanks

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If you replaced it with rubber hose, you need to make sure you use high pressure fuel injection hose.


If you used metal line and a compression fitting, you might have kinked one of the lines inside the fitting, killing the flow. In this case just buy a new fitting and try again.

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Alright, will try to check pressure. Not sure about filter, but everything was running fine (when it was leaking). It was after I spliced the line and took out the quick connect piece that it the motor started coughing.


Many thanks

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  • 1 month later...

Quick update: I'm paying my friend to teach me while he fixes my truck and here's what we've done so far


1. I removed the splice in the line and replaced the whole fuel return hose with proper fuel line (3/8")


2. checked engine compression (ok)


3. checked fuel pressure at the rail (35)


4. replaced distributor cap, wires, and rotor, and checked spark plugs


5. replaced the fuel filter


The truck is still bogging down. if i put it in neutral though it won't bog. only when it's in gear


My friend is suggesting I replace the distributor next to rule out a faulty sensor, but I'd rather not do that.


Any ideas?

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Some things i just ran across.

Truck took forever to get started, 15 second crank times.

It was hesitating and even backfiring under heavy load.


I Put a fuel pressure gauge on the rail. Specs are 31lbs at idle, 39lbs with regulator vacuum unhooked.

I had 26 lbs both ways....................problem there.

As soon as I shut the truck down it did not hold fuel pressure, dropped to zero pretty quick.................another problem.

I ordered a new pump and proceeded to to pull the unit from the tank.


Aha, the fuel line from the pump to the sending unit had softened to the point it was ready to fall off the sending unit.

I replaced the hose and used 2 new clamps, did not replace the pump.

Pressure at rail now at idle is 31lbs and 39lbs with regulator vacuum unhooked.

It now holds pressure when I shut the truck off and cranks times are now down to 3-5 seconds jamminz.gif


I would suggest you look into these readings because they are important, 35 lbs at idle is not right, make sure you have vacuum at the regulator

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  • 3 weeks later...

quick update. it's so weird that my oxygen sensor just happened to go out 5 minutes after I messed with the fuel line, but it was in fact the o2 sensor -- I guess.


I took my truck to the dealership mechanic. They said the computer said it was the o2 sensor and that they were going to replace it. 5 hours later, they said the Bosch o2 sensor didn't fit properly and they needed to order a new factory one. I said ok (for $150).


Then, when I was going to pay the bill, I realized that there is no "factory" that makes these (at least that's what I thought). I suspected I was getting a hose job, so I told them I'll just go buy the part myself. The dealership then did not charge me for any of the diagnostic labor.


After driving out of there, the bogging problem was fixed and hasn't been an issue in 2 weeks . . .? I don't know if them pulling the o2 sensor and messing with it somehow fixed it or what. Whatever they did though seems to have fixed it.


Anyway, wanted to pass along the update. Thanks again for all the comments and help, since I don't know what the hell I'm doing

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