TheSamba.com :: View topic - 70 square stalling when warm, missing if running

Tue Jun 10, 2008 5:26 pm

I really dont know much about fuel injection, I did read the manual, as well as Trams nice long sticky, but nothing jumped out at me.

my sons car really, I dont drive it much and neither does he, not a good car to be sitting in the college dorm parking lot for weeks at a time.

Ran great for me a few weeks ago, over Hecker Pass and back, 75 miles or so.

anyway, he drove it this weekend, hot weather, even in Santa Cruz, so he calls me to tell me the car died as he pulled off the freeway. Then would not start.

seems it happened the night before but he didn't tell me, thought it was low on oil :roll: so he put some in.

seems we must not have been clear about oil, he added some more the next day before talking to me.

anyway, I drove up to help out, and it started right up. Ran great for about 5 minutes as that was all I drove it.

We went to dinner with the family and picked up the square on the way home.

Seems it did it again on the way home. It was cool but the engine was obviously warm but not hot.

I started it in the driveway but ran very rough, rpms were very low almost dying without additional gas, but giving it more gas it sort of missed for about 10 seconds before the rpms got up to where they should be. Missing but no backfires, just low rumbling like maybe too much gas?

Looked in the engine compartment for missing wires, loose connections, or vacuum lines but didnt see anything.

by the way, I did have to drain out almost a quart of oil to get it to the correct level :evil:

suggestions?

cheers

peter

Tue Jun 10, 2008 5:49 pm

We were having problems with our 69 FI at one time. Pulling the distributor and cleaning the lower trigger points with a dollar bill got us running again! Bad voltage regulators are a problem on FI cars too.

Tue Jun 10, 2008 5:54 pm

Sounds like the fuel pump is starting to go, or the filter is plugged. Did you see my procedure on cleaning out the fuel pump with Diesel?

Get the car to run until it does it, and see if the fuel pump is hot. Careful, it might be hot enough to hurt. If it's hot, either the filter is plugged, or the pump is trying to seize. Stupid as it sounds, gas cools the pump so if the filter is plugged the pump is going to get hot, which boils the fuel like vapour lock. Change the filter, and, if the filter is THAT plugged, run the diesel fuel cleaning procedure on it anyways. If the filter is good, you've cleaned the pump, and it still does it, check the fuel pressure to be sure, but you're going to need a pump.

Tue Jun 10, 2008 5:58 pm

ok - quick troubleshooting for the symptoms y've described :

try to reproduce the failure

- check fuel pump (ignition on, do you hear a 2 sec buzz underneath the car)
- check fuel pressure (FI is very sensitive to low fuel pressure)
- check for false air, esplly. intake tubes rubbers (FI is very sensitive to false air)*
- when cranking do you have spark on ALL cyl?
- check points
- check temperature sensor (if sensor is broken, it shuts down the engine) or
if engine temperature was too high (less oil) it will shut down the engine
- check trigger contacts in your distributor

those are main points and checks I would run. Just my $.02: Don't change any component until you know the source of the cut out.

*IMHO: Since the car starts when cold and dies when warm: you may have an air leak. The cold start valve squirts additional fuel into the system. When your engine warms up, the amount of fuel gets reduced and put to 'normal'. Here is where your 'false air' comes into play: Your FI gets too much air and ergo your engine starts sputtering. So - after fuel pressure I would check for air leaks.

Cheerio
W

Tue Jun 10, 2008 7:19 pm

ok great leads, I will have a look in the am and will report back

thanks again to all, you are all a great resource

:D

peter

Thu Jul 03, 2008 7:26 am

update on this issue

I dont have a lot of time for these cars so it took awhile to get to it.

A friend that knows way more than I found that the trigger points in the distributer that set off the fuel injection were virtually closed or not opening correctly.

I dont drive it much so I had to wait for my son to come home and run it for a week.

Seems all is well in squareback land again

cheers

peter

Thu Jul 03, 2008 8:04 am

The "regular" points in the FI distributor that you access by taking off the cap do have a tendency to close up. The trigger points come out the side of the distributor after you've pulled the distributor out of the engine. Which set of points did your friend find the problem at?

Thu Jul 03, 2008 5:30 pm

Hate to say it but I was not there to watch :oops: but it was the trigger points that tell the injectors when to fire and not the plug wire points.