Need help diagnosing engine issue, stutter, shake, electrical discharge sound? Options

[narino]

I apologize for the long post.

First the info on the engine, low mileage rebuild done a few years ago. Originally a 1.7 that's been bored out to 2.5. It has dual weber IDF 40s.

I was headed down to meet up with a 914world member in San Diego when my car started to lose power. I had been on the road for about an hour when this happened. When I gave it more throttle the engine would do a stutter/shake, while simultaneously make a sound like a lot of static discharge (could that be the engine pinging?).

I pulled over and checked the engine bay. Every thing looked OK wire-wise. When I took the carb hats off I saw a cloud of "fine mist" in the throats. I blew it out and worked the throttle arm, it shot a strong stream of fuel into the carb throats and instantly misted up. I'm assuming this is normal?

After fiddling with the spark plugs I started her back up and got back on the road. The car ran fine for a few miles then the same thing happened.

Pulled over, blew out carb jets with cleaner, reassembled then got back on freeway. Again, drove fine no power issues for a few miles and then again the same stutter/shake.

Pulled over, I removed the 2nd fuel filter I had right before the Tee fitting for both carbs lines. Drove, a few miles later same issue.

Call AAA, tow home.

I don't have a temp gauge on the car so I can't tell if it's over heating. Though considering the engine is low mileage I wouldn't think that's the issue. Could it be an air leak in the manifold or somewhere that occurs when the engine reaches a certain temp?

I was so frustrated with this damn car when AAA showed up. Then as they were pulling her onto the flat bed I couldn't help thinking, "Man, she looks great in this light".
(IMG:style_emoticons/default/lol-2.gif)

TIA for any insight.

j

[bdstone914]

Sounds like overheating. Any thing caught into fan? All cooling tin in place?

[Dave_Darling]

Static discharge? Hmm, might be pinging. In my old 1.8, I thought it sounded like a "spitting rattle" noise. Check the timing, check for vacuum leaks. Also check for stuff that can make everything run too hot, like blockage in the fan and missing engine tin and such.

Has the car run fine in similar circumstances (temperature, trip length, etc.) before? Has anyone done anything to it since that time?

--DD

[narino]

DD - spitting rattle is exactly what it sounds like.

Good ideas on cooling tin, blockage, and timing I'll check today.

Since the rebuild this was the first time its been at highway speeds for that long. Previously all trips were quick spirited trips on canyon roads. The only "work" that's been done is taking off the top part of the carbs to clean out old fuel; I reused the old paper gasket.

Thankfully I'm in the first group for the temp gauge dipstick group buy. Will this dipstick be sufficient or should I be running additional gauges?

Hopefully i didnt do any major damage.

Thanks guys!

[bdstone914]

DD - spitting rattle is exactly what it sounds like.

Good ideas on cooling tin, blockage, and timing I'll check today.

Since the rebuild this was the first time its been at highway speeds for that long. Previously all trips were quick spirited trips on canyon roads. The only "work" that's been done is taking off the top part of the carbs to clean out old fuel; I reused the old paper gasket.

Thankfully I'm in the first group for the temp gauge dipstick group buy. Will this dipstick be sufficient or should I be running additional gauges?

Hopefully i didnt do any major damage.

Thanks guys!

Also check to see that the cooling flaps are opening all the way. Did you assemble the engine? Make sure the tins that go above the pushrods are in place. You may be able to see in there with a flashlight without removing the warm air guides. A couple of pictures of the tops and bottom of the engine may shed some light on the problem.

[narino]

I'll have to read up on how to check timing on a carb setup with petronix. Here are some photos of the engine bay and the underside.

Could a split paper gasket that meets the top and bottom half of the carb cause an issue like this?

Also, while under the car taking photos I saw some foam that was sandwiched between what I think is the oil cooler. Is that supposed to be there?

j

[PancakePorsche]

Shutter and shake is overly lean condition. Pinging is the result of the subsequent overheating. Indeed a fuel delivery issue. could be one carb, or both. May be sucking bowls low when freeway driving.

Bad pump / low pressure / low delivery
clogged tank sock / filters
kinked fuel line under tank
carb float drop adjustment / float level adjustment.........to name a few.

[Rand]

Did anybody read his post? This is so full of BS it's embarrassing. Stop replying, its only making you a fool.

[narino]

Rand - I'm not sure if you're being sarcastic or not. I'm a very novice mechanic therefore it's possible I'm not stating the information clearly. But the problem exists. Why would anyone post a fake thread? (IMG:style_emoticons/default/confused24.gif)

PanncakePorsche - I didn't know a lean condition could cause a temp rise? Sean_v8_914 thought it might be a fuel delivery issue as well, he was the member i was headed to see.

j

[Phoenix914]

Jorge, your car looks very clean. (IMG:style_emoticons/default/beer.gif)

Sorry, I can't help with the problem you are having.

Edit: sorry, I spelled your name wrong (IMG:style_emoticons/default/slap.gif)

[type47]

... I saw some foam that was sandwiched between what I think is the oil cooler.

you certainly don't want foam blocking the airflow over your oil cooler

[ChrisFoley]

Shutter and shake is overly lean condition. Pinging is the result of the subsequent overheating. Indeed a fuel delivery issue. could be one carb, or both. May be sucking bowls low when freeway driving.

Bad pump / low pressure / low delivery
clogged tank sock / filters
kinked fuel line under tank
carb float drop adjustment / float level adjustment.........to name a few.

(IMG:style_emoticons/default/agree.gif)

[narino]

... I saw some foam that was sandwiched between what I think is the oil cooler.

you certainly don't want foam blocking the airflow over your oil cooler

I thought that looked odd. I did not build this engine.

Home work so far:

1. Rip off foam block by oil cooler.
2. Try to pull/move the top tin to make sure they didn't install the cooling flaps backwards. Currently no thermostat, so they should be set to "cool".
3. Check to see if pushrod tube tin was installed. Had to do a search to find what/where this piece is. Good reference in this video. video link.
4. Learn to check timing on carb'd and petronix cars.
5. Check fuel pressure at carbs, and and any possible fuel delivery issues starting in tank. *edit add*
6. Read up on how to check air mixture with wide band sensor.
7. Check for vacuum leaks *edit add*
8. Possibly rebuild carbs.


Thanks for all the help! This is starting to venture into new territory so there will be quite a learning curve.

(IMG:style_emoticons/default/beer.gif)

* edited list to include things I missed.

[Dave_Darling]

I think I recall foam going around the cooler, to help air go through it. The foam should not be blocking air going into or coming out of the cooler, of course, but it might be that the foam is OK.

Don't forget checking for vacuum leaks.

--DD

[a few loose screws]

Id go back and check your work on those carbs. Make sure they are sealed up. a leaking gasket will cause a lean condition that will result in detonation and overheating. May save you some time. In most cases when diagnosing a system you want to start at point A and go from there, but I think since you were in to those carbs recently, you may want to make that your first stop. Good luck, hope you get it sorted out.

[Spoke]

Easy way to find a vacuum leak is with carb cleaner. Spray cleaner on any suspect gasket. If the idle changes likely you have found a leak.