Please help/ need advice, strange running problem Options

[ILM914]

Hello fellow 914ers: My car is misbehaving. When I first start it, I can drive out fine aside from being a bit sluggish due to being cold (normal). After it warms up it acts awfull, bucking very hard and hesitating, seemingly running on 2 cyl at times. I have adjusted the valves, timed the car, put some new ingition parts (car has elec ignition, no points). Symptoms don't improve when I disconnect the plug for the throttle body switch. The fuel pump is fairly new and I feel perhaps if it were fuel pressure or dirty injectors it would run poorly consistantly. I have not changed the spark plug wires and coil because I have never had these parts fail on any cars I have ever owned. I changed the dual points inside the distributor with tested good working used ones. I suspect perhaps fuel clog maybe in the tank or filter or perhaps the cyl head temp sensor? Please give any advise you think may help. Thank you. Someone else must have had this exact problem.

[markb]

I agree with a possible fuel clog. Replace the filter & see if it improves.

[type47]

Couldn't you put a pressure gauge in to measure fuel pressure, then when the running problem occurs, look at the gauge to tell if there is a clog? Low pressure= clog; OK pressure=something else? I'm thinkin' that if it was a clog, it would show up as hesitation/poor running at high or highway speeds where the fuel requirement is not met by the fuel pump output (clog actually limits the amount of fuel)

[dlee6204]

First off, tell us what engine you have and what system you are running (D-Jet, L-jet, etc.) so that we can better help you. I'm guessing D-Jet?

I can drive out fine aside from being a bit sluggish due to being cold (normal).

Can you elaborate on this a little bit? How is it sluggish?



Does it buck and hesitate through the entire rpm range or only at a certain spot? You say that it seems like it's running on 2 cylinders at times, so first I would suggest checking to make sure you have spark on all four cylinders when warm. Some other things to check...


-Check resistance of the CHT sensor (both when cold and warm)
-Fuel pressure
-Double check valves
-Double check timing
-If you don't know when the fuel filter was last replaced, it might be good idea to go ahead and replace that although your problem doesn't seem to be fuel starvation.



Also, where in NC are you? (IMG:style_emoticons/default/bye1.gif)

[windforfun]

Very bad TPS?

[ILM914]

Thanks Doug, yes D-jet when cold it runs pretty much like a cold 914 and I don't push it. The hesitation does occur in 4th and 5th gear (have to ride the clutch to keep the revs up and maintain 50 mph. hesitation seems to happen at all rpm ranges and at idle. then suddenly it will run fine, then bad again. Thank you, I am in Wilmington, NC know any car painters down here? my poor car needs exterior rust repair and paint. Thanks again, Joe

First off, tell us what engine you have and what system you are running (D-Jet, L-jet, etc.) so that we can better help you. I'm guessing D-Jet?

I can drive out fine aside from being a bit sluggish due to being cold (normal).

Can you elaborate on this a little bit? How is it sluggish?



Does it buck and hesitate through the entire rpm range or only at a certain spot? You say that it seems like it's running on 2 cylinders at times, so first I would suggest checking to make sure you have spark on all four cylinders when warm. Some other things to check...


-Check resistance of the CHT sensor (both when cold and warm)
-Fuel pressure
-Double check valves
-Double check timing
-If you don't know when the fuel filter was last replaced, it might be good idea to go ahead and replace that although your problem doesn't seem to be fuel starvation.



Also, where in NC are you? (IMG:style_emoticons/default/bye1.gif)

[Jeffs9146]

CHT Sensor!!!!!!

[tomh]

mine did the same thing then I bought a new harness from jeff and that solved the problem.CHECK YOUR WHOLE FI HARNESS FOR SHORTS OR CRACKED WIRES ECT.

[Jeffs9146]

mine did the same thing then I bought a new harness from jeff and that solved the problem.CHECK YOUR WHOLE FI HARNESS FOR SHORTS OR CRACKED WIRES ECT.

When I bought my 74 the PO, after rebuilding the motor, purchased and installed a replacement harness to try to fix the same symptom and ended up selling the car to me cheep when he couldn't track it down! I replaced the CHT Sensor a $17 part and in ran great!!

[tod914]

Look inside your gas tank with a flash light and see if it's clean. Possible crud/clogged strainer sock, bad gas maybe? Fuel pressure check like the other guys suggested would be a good start too. Good luck.

[mgphoto]

Hello,
A few months ago I had the same problem, see the link below.
It is the FI points in the base of the distributor, mine had dirty oil on the points, cleaned them and she runs like new!
Good luck,
Mike


http://www.914world.com/bbs2/index.php?sho...=113546&hl=

[indianmort]

could also be the coil. when cold runs fine as it warms up coil expands. if there is a break in the windings, the ignition will break down. when is cools off it will run fine again.

[McMark]

Have you eliminated the easy stuff first?
Adjust the valves.
Do a compression test to verify the condition of the engine.
Set the timing.
Replace the points/condenser if you still have them.
Are the cap and rotor in good shape?
Lots of little problems can add up to a big and confusing problem. Eliminate as much as you can before you start throwing $ and random parts at it.

[Kraftwerk]

I am watching this thread. Similar issue: starts fine on the first crank and runs like a champ, nice throttle response etc, actually quite peppy for a 1.7! But if I stop then re-start it, on the way home, it chokes and bucks and loses power. Some fuel /air issue, no doubt. Or maybe it doesn't want to go home, having way too much fun driving this car!
Just have to fix this running problem. It eventually 'settles' down after awhile, but on the road the bucking can be annoying.

[ILM914]

Ok I checked the fuel pressure, it read about 34 psi while running bad, So I kinda feel it's not a fuel filer or line clog. I noticed the wire from the harness to to cylender head temp sensor was suspect so I re-did the crimp connector. the bucking and exrtreme hesitation appears to have been solved by correcting this wire connection to the sensor, the connection may have been marginal before. The car will not run with that wire disconnected. Now I feel that the injestors need cleaning. any referalls for injector cleaning? Thanks guys. If your having a similar problem check your fuel pressure and basic elec ignition and check all the wires and connections and harness and ground points. Thanks Joe

s che fount that

I am watching this thread. Similar issue: starts fine on the first crank and runs like a champ, nice throttle response etc, actually quite peppy for a 1.7! But if I stop then re-start it, on the way home, it chokes and bucks and loses power. Some fuel /air issue, no doubt. Or maybe it doesn't want to go home, having way too much fun driving this car!
Just have to fix this running problem. It eventually 'settles' down after awhile, but on the road the bucking can be annoying.