Coughing under Throttle

[1987BlackJeep]

1053962

So my 87 YJ 4.0 straight six stutters under throttle some times on the highway (50-60 mph). Most often it happens when i am going up a hill in fifth gear, and have to down-shift to fourth and then to third to get back some power and to stop the hiccuping.

Anybody have any ideas of the cause?

:-? :-?


thanks [addsig]

 

[jcooper]

1053964

Is your fuel pump in the tank? I had the same problem a year or two ago with my TJ. Uphill, hiccupping, etc.
Ther was a leak after the fuel pump inside the tank. When in high throttle it would leak more. When the gas
sloshed (shifting gears) it would open the leak more. In both cases pressure would drop and it would hiccup.

Not sure if this info applies to the 87, but it's worth looking in to if the fuel pump in in the tank.

Cooper.[addsig]

 

[1987BlackJeep]

1053965

I dont know, but i will check it out.[addsig]

 

[MudderChuck]

1053966

Like Copper said anytime I hear stutter at 50-60 I think fuel pump. But then again, that RPM is when the ignition often starts breaking down, needs all the spark it can get.

Another thing you might look at is the float valve, if they get gummed up, it slows down the flow, the float bowl won´t fill fast enough, gets worse on hills.[addsig]

 

[jay89]

1053967

88 4.2 Cyl might help you!
OK, I had a similar problem.

I tried for months to fix it. It idled good, ran good, unless I need
power
for going up hills or highway driving.

There is a "rollover" valve, just in front of the gas tank. Looks like
a
small fuel pump. It's not. Disconnect the going to it from the tank,
and
the line going to the engine. put the ignition on, don't start it.
You
will have to put a small hose on the side that went to the tank. Try
and
blow through the valve. If no air can pass, the valve is no good.

I took mine off. Didn't see the need for it. After that, I had all
the
fuel I needed. Lots of power.

If it is just when you try to accelerate, it could be the accel. pump.

edited by: jay89, Feb 06, 2003 - 04:33 PM[addsig]

 

[1987BlackJeep]

1053970

I suppose when I look at it, I will understand what valve you are talking about. But, do you mean that you just removed it and that solved the problem? Or did you replace it with a valve that was not clogged?[addsig]