Jerking While Driving and... Stall

[Scotty]

This problem comes out of nowhere. Last time I had this problem I was driving and the car started jerking, as if it was getting not enough gas and then stalled. The fuel pump was boiling and it took me awhile to limp the Alpine back home by starting, jerking, stalling and coasting. Since then, the car has gotten an Oil Cooler which has GREATLY increased PSI in the 1725 to a respectable 30-35 PSI at hot idle. Also tossed the plastic fuel filter and installed a Tim R Special: ran the fuel line from the pump and around the engine to the Weber with a one-way valve in-line. The fuel pump has ran to 90 degrees I took the car out in, including a really hot day and did beautifully.

Until today.

I went and filled the tank at Chevron and took the car for a run. About a mile down the road the car jerked repeatedly and then stalled as I managed to coast it off the street and into a parking lot. I checked the engine bay and see the fuel pump bubbling along again, not as bad as the last time, but still noticeable. I checked the balance hoses. I opened the gas cap. No sounds. No hisses. Nothing. I started the car with the gas cap open and it fired up. No movement or weird bubbling in the tank that I could see with a flashlight. I closed the cap and drove it home, like before, jerking, stalling, coasting and restarting on my way. Once again my marvelous fiancee was driving behind me being my hero.

Once it cools down, I'm going to pop the top off the fuel pump and see what's inside. I have an electric fuel pump sitting on my shelf in case it's time. Both tanks are relatively new with one of them brand new thanks to my best friend in the whole world Al Mason.

I went through and had just put in new Autolite 63's and made a wireset that's more fun than it should be. Checked spark a moment ago and all plugs are getting spark. Eyeing my electronic ignition just in case the problem is really electrical since most general issues wind up being on the ignition side... I don't know, just trying to work this all out.

That's about all I know to do in this situation. Where is this all going wrong? What should I do?

 

[Mike Berger]

This problem comes out of nowhere. Last time I had this problem I was driving and the car started jerking, as if it was getting not enough gas and then stalled. The fuel pump was boiling and it took me awhile to limp the Alpine back home by starting, jerking, stalling and coasting. Since then, the car has gotten an Oil Cooler which has GREATLY increased PSI in the 1725 to a respectable 30-35 PSI at hot idle. Also tossed the plastic fuel filter and installed a Tim R Special: ran the fuel line from the pump and around the engine to the Weber with a one-way valve in-line. The fuel pump has ran to 90 degrees I took the car out in, including a really hot day and did beautifully.

Until today.

I went and filled the tank at Chevron and took the car for a run. About a mile down the road the car jerked repeatedly and then stalled as I managed to coast it off the street and into a parking lot. I checked the engine bay and see the fuel pump bubbling along again, not as bad as the last time, but still noticeable. I checked the balance hoses. I opened the gas cap. No sounds. No hisses. Nothing. I started the car with the gas cap open and it fired up. No movement or weird bubbling in the tank that I could see with a flashlight. I closed the cap and drove it home, like before, jerking, stalling, coasting and restarting on my way. Once again my marvelous fiancee was driving behind me being my hero.

Once it cools down, I'm going to pop the top off the fuel pump and see what's inside. I have an electric fuel pump sitting on my shelf in case it's time. Both tanks are relatively new with one of them brand new thanks to my best friend in the whole world Al Mason.

I went through and had just put in new Autolite 63's and made a wireset that's more fun than it should be. Checked spark a moment ago and all plugs are getting spark. Eyeing my electronic ignition just in case the problem is really electrical since most general issues wind up being on the ignition side... I don't know, just trying to work this all out.

That's about all I know to do in this situation. Where is this all going wrong? What should I do?

Check the ignition switch.

 

[todd reid]

paint flaking off gas tank(s)? replace fuel filter and cut old one open.

 

[Scotty]

paint flaking off gas tank(s)? replace fuel filter and cut old one open.

Don't have one before the pump, had one after the pump and it stayed fairly clean. Took the glass dome off the pump and found a hole in the mesh screen. Pulled the top off the Weber and the float bowl is clean. Put the Weber back together, cleaned out the fuel pump and the sediment out, put it back together, primed, restarted the car and at stone cold it's bubbling. I think the pump is the problem, but would like someone more knowledgeable than me verify it.

Went through the ignition side and the electronic ignition and all systems look go. Might replace the electronic ignition module just in case even though it's less than a year old.

 

[todd reid]

if you are seeing air bubbles in the fuel, then I think you are on the right track - sounds like a fuel pump issue - assuming your fuel lines are solid .

TR

 

[Scotty]

I did today the one thing I should have started with yesterday: Unhooked the Fuel Pump line, put it in a bottle and see if it would fill it. Ran the car with starter only for a few seconds and got a stready stream of gas out the hose, so unless there's something else I should check, the pump is fine beyond needing a new screen. I think my problem is electrical.

I'm running a generic 25D4 electronic ignition (Hot Spark) with correct can coil and wires. Wondering if the electronic ignition or coil are misbehaving.

Check the ignition switch.

What's the best way to do this?

 

[mxp01]

Scotty,

Have you looked at your rotor cap in a while? The tip of cap that makes contact with each plug wire lead on the distributor cap starts to build carbon over time along with the leads inside of the distributor cap. If these areas build up with carbon it can cause a misfire.

I clean mine every year with a scotch bright pad to keep a good clean contact.

 

[Tim R]

In the U.K.we have had a lot of problems with dodgy rotor arms. Well worth checking that what you have is correct, no rivet on top and the correct diameter.
From your description I would also ask:
1/ When you see the fuel 'boiling' is it actually boiling or is there a defect in the pump that is making it blow air into the fuel?
2/ Have you tried substituting the distributor and separately, the HT leads?
3/ Do you have the insulators (and gaskets) both under the carb and between the fuel pump and the block?

Tim R

 

[Scotty]

Scotty,

Have you looked at your rotor cap in a while? The tip of cap that makes contact with each plug wire lead on the distributor cap starts to build carbon over time along with the leads inside of the distributor cap. If these areas build up with carbon it can cause a misfire.

I clean mine every year with a scotch bright pad to keep a good clean contact.

I have a spare rotor cap, I'll change that today. I'll sit down and clean up the other one since it does have carbon on it like you said, didn't know it could be cleaned, thank you for that!

In the U.K.we have had a lot of problems with dodgy rotor arms. Well worth checking that what you have is correct, no rivet on top and the correct diameter.
From your description I would also ask:
1/ When you see the fuel 'boiling' is it actually boiling or is there a defect in the pump that is making it blow air into the fuel?
2/ Have you tried substituting the distributor and separately, the HT leads?
3/ Do you have the insulators (and gaskets) both under the carb and between the fuel pump and the block?

Tim R

I took your advice and had bought a few rotor arms from one of the UK dealers you had used and that one still looks pretty good.

When the fuel boils, I use a Thermo gun on it and it tends to be around 120 degrees. With the addition of the Oil Cooler it's sitting at 90. This last time it was 110 and had the problem this thread is named after.

I don't have a spare distributor to swap out or I'd try that. The HT leads are literally a few days old.

I have neither spacer, where can I get those? Does the spacer for the fuel pump move the lever away from the Cam? Concerned about it damaging anything.

One thing I noticed on my car is that the Ignition Coil is the same one that came on the car when I got it in 04 and I thought nothing of it. My grandfather has told me and my dad stories about how it can get warm and seperate the wiring inside and cause. Is this true? I'm picking up a new one in the hour to swap them out.

And here's a question for the more tech-savy folks out there: Is there a way to test the electronic ignition to see if the problem may lie in there. When I thought heat, I thought of electronics swelling up and causing things to seperate and well... stop working. Looking for a reliable way to check the system before ordering stuff and tearing things apart.

TRYING to be patient here and that's a new thing for me lol.

 

[Tim R]

Scotty,
It could be the coil degrading but if you don't have the spacers that is your problem. I would be surprised if both were missing though.
There is an insulator with gaskets both sides between the carb and the inlet manifold and the fuel pump and the block. I've put some photos below. The fuel pump insulator is different on an Alpine as the holes are not level with each other but it looks roughly like this. The amount that the fuel pump is moved in and out with gaskets determines the amount of fuel it pumps. The manual details how to make changes, if you have to fit the spacers when you refit the pump ensure that the tip of the pump arm is riding correctly on the cam lobe and doesn't get wedged beneath it. Look carefully at your car, the spacers may well be there already.
Are your HT leads copper or silicone? Several of us in the UK have had issues with silicone ones causing running problems. Switching to copper HT leads cured it.

90* Fahrenheit is 32* centigrade. That is only a little below the 36* point where modern petrol can start to boil (dependent ion the mix) so it may well still be boiling through heat soak.

Tim R

 

[husky drvr]

And here's a question for the more tech-savvy folks out there: Is there a way to test the electronic ignition to see if the problem may lie in there. When I thought heat, I thought of electronics swelling up and causing things to separate and well... stop working. Looking for a reliable way to check the system before ordering stuff and tearing things apart.

Scotty,

Here's a thought to help channel your search.

Electronic components are generally like a tungsten filament in a light bulb - it's either good or bad with not much in between.

If it's an electronic issue due to heat soak that comes and goes, the component will almost certainly have to cool down to "reset" the problem.

You seem to have an issue that is a short duration, intermittent problem - or a combination of more than one issue.

Just as a basic Lucas electrical check-up, you should check your starter switch, power connections, and grounds. The starter switch has already been suggested by Mike Berger, and is a good place to begin because it's designed to be an intermittent connection and is known to be a wear item. Please don't burn down your car.

Are you running the PCV (Positive Crankcase Ventilation) system? If so, what valve and how is everything hooked up?

Just a thought,

 

[Scotty]

Scotty,

Here's a thought to help channel your search.

Electronic components are generally like a tungsten filament in a light bulb - it's either good or bad with not much in between.

If it's an electronic issue due to heat soak that comes and goes, the component will almost certainly have to cool down to "reset" the problem.

You seem to have an issue that is a short duration, intermittent problem - or a combination of more than one issue.

Just as a basic Lucas electrical check-up, you should check your starter switch, power connections, and grounds. The starter switch has already been suggested by Mike Berger, and is a good place to begin because it's designed to be an intermittent connection and is known to be a wear item. Please don't burn down your car.

Are you running the PCV (Positive Crankcase Ventilation) system? If so, what valve and how is everything hooked up?

Just a thought,

Gotcha. I'll begin checking through the list of things tomorrow!

I'm considering removing the electronic ignition temporarily and putting back in a new set of points and condenser that I have in my emergency kit just to test things out.

In my mind, it's either the coil or the electronic ignition, but if it's worth doing half-ass, it's worth doing right, so I'm going to follow your advice and check everything. Hurts nothing.

My PCV setup is a hose coming from the side of the oil fill-in on the valve cover that goes down the back of the engine to the side of the transmission and vents to atmosphere. If plumbing it with a flame trap to the Weber 32/36 would make things better, I'd do it, but I've been told by several people that it's better for the car do it in this fashion. If this is wrong, someone please tell me.

 

[husky drvr]

My PCV setup is a hose coming from the side of the oil fill-in

Is there a hose from the engine's side tappet cover to the manifold?

 

[Scotty]

Is there a hose from the engine's side tappet cover to the manifold?

Yes, it goes from the hose connection on the tappet cover and goes to the right side of the manifold (if facing the manifold from the drivers side of the engine bay.)

 

[husky drvr]

Yes, it goes from the hose connection on the tappet cover and goes to the right side of the manifold

Okay, is it just a hollow hose connection or is there something movable plugging the hole?

Pictures might help.

 

[Scotty]

Okay, is it just a hollow hose connection or is there something movable plugging the hole?

Pictures might help.

It's just a hollow hose connection, from the tappet cover hose connector to the connector on this:

The manifold does have a few things plugging parts of it, one of which I think is/was a water passage.

 

[husky drvr]

just a hollow hose connection

That would be a problem. It should have this stuff in it. You could test with a wire. If the wire only goes about half way through, the parts are probably there. If the wire goes deep enough to reach into the manifold, the parts are missing.

If the parts are missing, plug the port and see if you can start the car. Options can be discussed then.

 

[Scotty]

That would be a problem. It should have this stuff in it. You could test with a wire. If the wire only goes about half way through, the parts are probably there. If the wire goes deep enough to reach into the manifold, the parts are missing.

If the parts are missing, plug the port and see if you can start the car. Options can be discussed then.



View attachment 32455

It does have that plug unit between the manifold and hose. I looked at it when I got back and noticed how that sits a little up on the manifold and not directly on it and see why. Yes, this is installed. I don't have the flame trap and that hose just trails off to vent to atmosphere.

What is important about the tappet cover/manifold hose setup? Could this be causing my problem? I'm sorry, I have no frame of reference but am going to try and read up on this.

I did some reading through other posts and found Tim R saying that he vents both hoses to atmosphere and plugs the manifold side. What are the benefits to this, if any? Does it help the 1725 run better or does it need it to run better?

 

[husky drvr]

It does have that plug unit between the manifold and hose. I looked at it when I got back and noticed how that sits a little up on the manifold and not directly on it and see why. Yes, this is installed. I don't have the flame trap and that hose just trails off to vent to atmosphere.

What is important about the tappet cover/manifold hose setup? Could this be causing my problem? I'm sorry, I have no frame of reference but am going to try and read up on this.

That's the actual PCV valve. It's supposed to meter the crankcase gases to be burned by the engine. The valve is controlled by engine load (vacuum). If the valve is stuck open, it's a massive vacuum leak. It's supposed to be disassembled and cleaned regularly. New ones are not available and haven't been for ages (maybe some work- a-rounds).

If you want to read up on these, there are two pages in WSM 124 starting on the page number in the above illustration.

 

[Scotty]

That's the actual PCV valve. It's supposed to meter the crankcase gases to be burned by the engine. The valve is controlled by engine load (vacuum). If the valve is stuck open, it's a massive vacuum leak. It's supposed to be disassembled and cleaned regularly. New ones are not available and haven't been for ages (maybe some work- a-rounds).

If you want to read up on these, there are two pages in WSM 124 starting on the page number in the above illustration.

Is it necessary to have this installed? What are the benefits of keeping it? I'm going to pull it tomorrow and toss it in the Ultrasonic Cleaner.

Taking it off to clean as we speak.