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Sun Jul 15, 2012 11:29 am

When it runs good, it runs VERY good, but it seems after running for a while - as short as ten minutes - it stumbles and quits like it's running out of fuel. Yesterday I had it running in my driveway for 30 minutes, idling and revving - it ran great, Was just about to take it for a road test, when it stumbled and died.
Some history... it sat for a long time, close to 15 years.
New aftermarket electric fuel pump - "OE quality" from CIP1
all new rubber FI fuel lines
new filter (changed twice)
gas tank looked to be fairly clean inside
new points & condensor, plugs and ignition coil
all new engine vacuum lines, clamps on the larger hoses
new injectors
new air filter element
new double relay
every electrical connection has been cleaned or looks clean
new temp sensor
The air intake sensor tested fine - 280 ohms on #6 & #9, 190 ohms on #7 & #8, no continuity when the door is closed on #36 & #39, continuity when opened slightly
Ignition timing is dead on with the marks
new gas cap
all the tank vent lines are in place
charcoal cannister is not connected to the air breather box
The fuel pump seems noisy, today when I connected my homemade pressure tester it only got up to 25 psi and the engine would not idle by itself. It did so yesterday before it died. It also didn't want to accelerate today either, with some minor backfires and lot of stumbling. Hard to start today too.
When I changed out the vacuum hoses yesterday, the only hose not changed was the breather line from the base of the oil filler to the S boot. The hose that is on there seemed to barely in place, so I cleaned it and reconnected it, but the hose is old and hard and seems too short. I'll replace it tomorrow with a new piece.
I don't know at this point if the fuel pump is bad, or maybe the breather line is giving me trouble causing a vacuum leak.
When I changed the coil a couple weeks ago, I thought it was cured. It ran well for a couple hours.
It does seem to me to run hot, hotter than my 74 SB ???
I should mention the EGR is still there, but not connected to the exhaust. The tube is still open at the bottom.
As I said, when it runs well, it rus very well. We drove it for 45 minutes earlier this week before it died and had to be towed home. When we drive it, it gets revved out pretty well, not babied.
This is not my car and am only putting it back together after doing the body and paint. No idea why it was parked so long ago or even how it ran back then.
I'd really like to get it running better ALL the time and get it out of my driveway.
Any help would be greatly appreciated!

Sun Jul 15, 2012 11:54 am

Where in southern ON? Try swapping out the coil. I had a coil one time that over heated after 30 mins driving and then just sputtered and died until it cooled off and off I went again until it over heated again.

Sun Jul 15, 2012 12:32 pm

Sarnia. ;)
I replaced the coil a week or two ago. For a short while it seemed to be the cure, but no go.

Sun Jul 15, 2012 2:50 pm

Have you checked the air intake boot? Thats the rubber bit that runs to the AFM. My 76' had the same sort of problem, it would run amazing, and then sometimes it would just stumble on idle and die, or when i was out driving, it would start to lose power and stumble. Finally discovered that my intake boot was really cracked, and it was sucking air in instead of fuel. Apparently its quite common :shock:
Just my two cents.

Sun Jul 15, 2012 3:49 pm

Try another condenser. It is pretty cheap and I've seen ones that fail when they are hot.

Sun Jul 15, 2012 4:01 pm

Check colour of the plugs and how the engine temp. Oh and another Canadian. lol.

Sun Jul 15, 2012 5:09 pm

You have to have 26 psi in the fuel rail to even get it to start.

If it were me, I would do a fuel pressure test and see if the fuel pump or the fuel pressure regualtor is the culprit.

Been here?

http://www.itinerant-air-cooled.com/viewtopic.php?f=42&t=213

Sun Jul 15, 2012 6:06 pm

I checked the intake boot way back when I was first putting the thing back together, it looked ok. I'll give it a more thorough inspection tomorrow when I change the breather hose.
Changed out the condensor the same time I put in the new coil. I was thinking the same thing - cheap fix.
The plugs look alright, darker tan the last time I pulled one.
I've bookmarked the itinerant site. When I tested the fuel pressure I connected the gauge at the cold start valve. 25 psi was the max reading I got, but perhaps my gauge is off a little - it's actually an oil pressure gauge.
Thanks for all the help. I'm pulling out my already thinning hair... :)

Mon Jul 16, 2012 6:41 pm

So.. gave the intake boot a good going over - no cracks or tears anywhere. Changed the hose from the oil filler stand to the intake boot (NOT a fun job!), put it back together and ran it for 10 minutes or so this evening. It runs ok, seems to idle a little slower than it did before - maybe the hose was leaking?
Connected my fuel pressure gauge ( a real one) and it held a constant 30 psi for those ten minutes.
I'll run it tomorrow for a longer time and watch the pressure gauge as it runs. I've got my fingers crossed...[/i]

Mon Jul 16, 2012 6:57 pm

The important part of the test is with and without the vacuum line hooked to the fuel pressure regulator.

You are getting closer.

Wed Jul 18, 2012 6:26 pm

I ran it for a good hour and a half this afternoon, with the fuel gauge connected, in my driveway. Pressure never wavered from 28 psi and it ran beautiful
Felt like it was running cooler as well, but air temp today was 80F, much cooler than it has been.
Disconnected the gauge, went for a ride and made it back home without a tow truck! But, any heavy acceleration made it stumble like it was out of gas.
Hooked the gauge back up, still at 28 psi. Disconnected the vacuum line from the regulator, the gauge went to 30 psi and stayed there.
I ordered a new regulator, it'll be here Friday.
Any secrets to making the swap easier? It's in a real awkward spot...

This car has had sooo many problems, it's been one after another. The owner told me they drove it on occasion as late as 2000, but with as many issues that I've run into, I doubt that very much. When I first started on getting it back together, I found someone had by-passed the regulator. Now I know why.

Wed Jul 18, 2012 6:46 pm

If under load its starving for fuel. That means it's too lean or not enough fuel. Cheek also you vacuum advance is working correctly. Maybe it's stumbling because of advance.

Wed Jul 18, 2012 9:18 pm

The EGR valve is there but not connected to the exhaust? If so unplug the EGR can from vacuum. Exhaust doesn't contain oxygen (O2) so it doesn't cause the engine to run lean if you let a little in. Letting a little air in will cause it to go lean.

I have the EGR on my '79 but I have pulled vacuum from both the EGR and decel valve. They don't do anything anymore.

Mon Jul 23, 2012 6:11 pm

In stalled the new Bosch regulator Sunday (very low on my list of fun things to do on a Sunday afternoon), put it all back together, started it up and it ran like a champ. Short drive around the block when it ran very nice. Fuel pressure is at 28psi, goes up to 35psi when the vacuum line is disconnected.
I'm thinking we've got it beat. :)
Today, it runs like it did two weeks ago. Connected my gauge, runs 26-28psi and slowly drops off as the engine stumbles. Disconnect the vacuum line, start it back up the pressure is higher but declines as the engine stumbles.
I went back over all the vacuum lines, disconnected and plugged the EGR line just in case, tested the air intake sensor again, double checked to make sure I didn't have a fuel line kinked... everything checks out ok.

I'm ready to burn the car...

Any thoughts?

Anyone?

Mon Jul 23, 2012 8:25 pm

Check that the vacuum draw on the regulator is correct. After giving up on mine I took it to a shop that found that to be the problem on.

Tue Jul 24, 2012 10:41 am

Wouldn't that give higher pressure instead of losing pressure?
I don't have a vacuum tester, I'll have to borrow one.

Tue Jul 24, 2012 2:07 pm

If the vacuum is too strong, yes. Too weak, not enough pressure. Mine tested at 30-38 in my garage so I thought it was good. They did'nt explain in too much detail, but they did tell me that the problem with mine was incorrect vacuum at the regulator. This was the Volksdoktor in Louisville. They have a great reputation. I'm not good enough with fuel injection to know any more than that, but it does run fine now. Good luck

Thu Aug 02, 2012 6:53 pm

I installed a new Bosch fuel pump on Wednesday, replaced the fuel filter while I was there.
That solved it.
No more noise from the pump.
Runs and accelerates beautifully.
Constant fuel pressure.

A three hour ride this evening and we made it home without the tow truck! :)
Thanks for the help!

Mike