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-   -   Charging woes (http://forums.pelicanparts.com/porsche-914-914-6-technical-forum/231943-charging-woes.html)

robertj 07-19-2005 05:43 PM

Charging woes
 
I know that there have been many a post on the electrical system and technical articles written that I've read as well, but here's my problem:

I just bought a 75 2.0 model, and it seemed to run a bit rough in 1st and 2nd gear and rough, but not as bad in 3,4 and 5th gears. That is unless I really stomped on the gas, then it would take off. However, the last week it really wasn't moving well even when I stepped on it, and often would lug before accelerating. I was hoping a fuel filter change along with new fuel lines would remedy that. Before I could get to that job though, the engine quit on me while on the freeway. It was running really rough before that, even backingfiring. When it quit, I was able to compression start it, but it quit again after a minute or so and wouldn't restart.
I also couldn't get the headlights to come up after it quit, although the hazard lights seemed to work ok.

I had it towed to my house, and there it sits. From past car experiences I'm thinking it could be the alternator- I've been able to jump the car, and it seems to run good for a short time while connected to the other car's battery, but as soon as it's disconnected it will begin to run rough again, and I can't keep it going for longer then 20 seconds or so.

It was suggested that I charge the battery overnight, and then see how it runs, as a fully charged battery should allow it to run good for a few minutes.

The problem is that I don't have any experience measuring voltage (maybe time to learn?) or the equipment to do so, unless the voltveter I use for computer repair will work.

Is the alternator a safe bet? If it was going out, would it cause the engine to run really rough? If I disconnet the battery, will the control brain settings get messed up? The engine has been converted to hydraulic lifters (something else I don't fully understand yet either) in case that makes a difference.

Any help would be greatly appreciated.

...also, regarding the part of the pellican article about removing the alternator, where are the plastic covers on the engine tin that need to be removed? All I can see is metal parts attached to the engine tin, plus I can't seem to feel my way to the pinch bolt. Is there a picture of this somewhere that would help deomonstrate this section of the removal? (The Hanes manual hasn't helped me in this area)

Thank you all so much!

-Robert

Dave at Pelican Parts 07-19-2005 06:23 PM

The voltmeter you use for the computer stuff should be fine, as long as it has a 0-20VDC range. An automotive electrical system runs on "12 volts" (more like 14V in practice), so you need something that can measure that range.

As for how, just poke one probe of the voltmeter onto the + post of the battery, and the other onto the - post. With the engine off, a fully charged battery should show about 12.6V. With the engine running, you should see between 13.5 and 14.5V unless the electrical system is heavily loaded (lights, etc.).

One of the plastic covers is shown in Haynes, Fig. 1.14 "Fan, fan casing and associated parts" (p. 22 in my copy). It's part #1 in that diagram. The other cover is "around the corner" from there, on the side part of the engine tin.

A really bad alternator might cause some running problems, but my car (when it still had points) ran just fine until the system voltage dropped below about 9V--which is really dead. The alternator had failed, and I had to jumpstart the car and drive ~45 minutes home because the battery was completely flat. I made it to within a few blocks--I had to stop at a red light, and the draw from the brake lights was enough to drop the system voltage below the point where the injection worked. Apart from having the motor cut out when I used the turn signals (same problem), no driveability problems on the way home until then.

So I doubt the alternator is your running problem, though it is possible.

If you run the engine with the battery disconnected, you risk blowing some of the diodes in the alternator and possibly damaging some of the other electrical parts in the car. That is not recommended procedure....

--DD

robertj 07-24-2005 08:42 PM

So in replacing the fuel lines I found that I had an injector with a cracked head. (I'm guessing that isn't the technical term for the green casing that surrounds the tip of the injector, but what the heck.)
I'm really hoping that replacing this part (along with the fuel lines and fuel filter) will go a long way to help fix how badly the car wa running.


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