Motor Problems

[dman007]

I am posting this message for my brother that doesn't have access to the internet. He recently bought a '71 914 1.7 (has stock fuel injection) that was undriveable because of a clutch problem. However, he was able to start the motor which seemed to run alright. He proceeded to take out the motor and trans to work on both. He did fix/replace the clutch and related parts. He also adjusted the valves, replaced all the vacumn lines, replaced all the fuel lines, replaced all sensors I believe, cleaned up the electrical connetions and wiring and replaced all parts associtaed with a major tune-up. He put the motor/trans. back in and was able to fire-up the motor after doing some minor electrical troubleshooting. Now here is the problem(s) or should I say symptoms. If he sets the timing to where it should be(@ 3,500 rpm), the idle wants to "hunt" between 1,000 and 2,000 rpm. If you adjust the distributor(I am not sure which way at this point)the "hunting" will go away. Now if you drive the car, especially after it warms up, the motor wants to cutout bad at about 3,500-4,000 rpm. It sounds and acts like a rev-limiter. Remember, all parts such as the dist. rotor were replaced. He also tried putting in the old one with the same results. Does anyone have any ideas or suggestions?

[Dave at Pelican Parts]

The "hunting" at idle is a classic sign of a lean idle mixture. 1000-2000 RPM is pretty high for that, but... After late 71, the ECU ("brain box") acquired a knob on the top side. Turn this knob clockwise to richen the idle mixture (only), and CCW to lean the idle mixture. If your brother's car is not a late 71, he won't have that option.

The timing is correct when it shows 27 degrees BTDC at 3500 RPM with the vaccuum hoses disconnected. The timing mark is about four fan blades from one of the four "posts" that hold the front and rear halves of the fan together. If your buddy has mucked with the timing much, that might cause the bucking at 4000 RPM.

Make sure the ignition system is up to snuff. I know it's new, but it is still worth making sure. Check the dwell and the condition of all the components.

Also check the fuel pressure. It should be right around 30 PSI--from 29-32 should be OK. Low fuel pressure could cause a lean mixture.

Check the head temp sender. Resistance should be around 3K ohms cold-cold, and low (<200?) when warm. Too low a resistance will give a leaner mixture.

As a temporary fix, your buddy could put a 0-3K ohm potentiometer between the head temp sender and the wiring harness. More resitance will make the mixture richer.

Kjell Nelin has a very nice article on the D-jet system. It's worth checking out. It lives in the Tech Refs section of Tim's 914 Fan Page, .

Good luck!

--DD

[JP Noonan]

Sounds familiar, I traced my problem (for the most part) to rust on the advance weights. What happened is while I was freshening up the motor with new ing. components, seals, and gereral cleaning, I decided to dismantle and clean the dizzy. Unfortunately I didn't re-oil the inside parts so rust was making the advance weights stick. Remove the dist. then remove the vac advance and the plate that holds the points. Under that are the weights. It isn't easy to clean them because the weights are near impossible to remove, just use penitrating oil and contact/electric motor cleaner. You should be able to spin the drive shaft like a top and see the weights spread out.

[Sharkbait]

I had that problem too- I went through alot of stuff then I replaced the fuel pump and my problem was solved!