Fuel starvation and hot coil

[Doug&Deb]

Today I had a problem with my 52 Coronet. It just drops to idle while driving. It feels like vapor lock. Turning on the auxiliary electric pump cures the problem but I’m still confused why it started happening again. I fought this issue a few months ago and thought I had it fixed. I’m also wondering how hot is normal for the coil. I checked it after I got home and it’s hot but not to the point that I can’t touch it or have to remove my hand. Is that normal or is that part of the problem? I’m not sure how the electric pump would fix a bad coil though. Still thinking fuel issue. Any thoughts?

[TodFitch]

If turning on the electric pump cures it then it is a fuel delivery problem.

[keithb7]

I’m thinking there may be more than one thing going on here.  What sort of ambient temps are you seeing?

[Doug&Deb]

Keith it’s high 80’s and humid so definitely a factor. I changed the coil just for the heck of it. No improvement. I checked the pump while the car was running. I thought maybe the pin was moving. I noticed that the fuel in the sediment bowl was full of bubbles. The car actually stalled while I was under it. I got it started with the electric pump on and the fuel in the bowl was back to normal. No bubbles and a good supply. It runs great with the electric pump on so for now that’s the solution. I definitely understand why people switch to electric pumps on old cars. Ethanol gas really sucks.

[Doug&Deb]

As an aside, my engine temperature is 160 and the fuel line from the pump to the carb is as far away from the manifold as possible and insulated. The heat shield is in place also. 

[Sniper]

If you have bubbles in the fuel line odds are you have some pinholes in a rubber line and the mechanical pump is sucking air.

 

Which means with an electric pump odds are you'll have fuel leaks soon.

[Los_Control]

My opinion on the coil, it will be at least as hot as the engine it is attached to ..... Mine is mounted to a metal bracket bolted to the head .... the heat will just transfer to the coil.

Also the engine bay is like a oven .... the internal engine parts affected by the cooling system is 160F .... I guarantee the exhaust manifold is not 160F .... no idea what kind of air flow or exchange these cars have under the hood .... then to top it off, the coil makes voltage and that creates heat ..... it is normal for a coil to be hot imho.

When it literally burns you when you touch it, then it may be time to replace.

[keithb7]

If you are working with an old car with unknown age of fuel tank, fuel lines, there’s plenty of things that can happen. Sediment. Scale. Rust. Water in tank. Leaking fittings. Crusty fuel hoses. Chunks in the carb inlet valve. SedIment in the bowl. Partially plugged jets. Failing rubber in the fuel pump. Accelerator pump. On and on. There’s been a few posts lately on the topic. Sorry if I mix up the details.

 

In general, understanding the basics, what something is supposed to do, how it interacts with something else, how it contributes to a properly running engine, will help you tremendously in diagnosing the problem. 
 

Your coil is oil filled to keep it cool. How cool? I’m unsure. I’ve never ran a laser thermometer on it after a drive on a hot day. I’ll do maybe next time I am out in my old Mopar. I’m interested is seeing how hot it gets. 
 

Are you running the stock 6V system with positive ground, and 6V battery? 
 

 

Edited June 30 by keithb7

[Doug&Deb]

Stock 6 volt positive ground. New tank and all lines metal and rubber. New fuel pump also. Pivot pin hasn’t moved so that’s not the issue. The carb is a cheap swap meet find and I haven’t done anything to it yet but I don’t think the electric pump would cure carb issues. I did have to tighten the inlet and outlet fittings on the pump. I once cracked a new pump by over tightening the fittings so I’m always worried about that. I probably didn’t have them tight enough. Tomorrow isn’t supposed to be so hot so I’ll see how it goes.

[Bingster]

My coil got very hot on first start attempts, and so I got a new one. Same deal. Doesn't seem right. I think that maybe the prolonged starting of the engine may have done this. I don't know. I think my problem is the carb, so I'm going in it to see what's in there that shouldn't be. Have been watching Keith's video on the carb which is very informative.

[Los_Control]

1 hour ago, Bingster said:

My coil got very hot on first start attempts, and so I got a new one. Same deal. Doesn't seem right. I think that maybe the prolonged starting of the engine may have done this. I don't know. I think my problem is the carb, so I'm going in it to see what's in there that shouldn't be. Have been watching Keith's video on the carb which is very informative.

Maybe I need to go back and revisit your thread on that ..... I think there were some questions on if you were using a 12V battery on a 6V system.

And if you were, you should have a ballast resistor in place. .... The 12V battery will make your coil hot. .... will not prevent your car from starting though.

If you leave it this way eventually will probably burn the coil out.

All the ballast resistor does is reduce the voltage coming from the 12V battery to 6V which the coil is prepared to handle ..... unless you add a 12V coil that does not need a external resistor.

 

I'm switching to 12V so I need these items.

 

 

 

 

 

 

I'm just saying, you can use a 12V battery to start it ..... it will make your coil hot unless you properly address the issues .... I just never saw your reply back on what battery you were using.

[Bingster]

I have 6v Keith, and why are you switching?

[keithb7]

3 minutes ago, Bingster said:

I have 6v Keith, and why are you switching?

I don’t think I’m switching anything. Did I elude that I was? Sorry. 
 

Can you explain a bit more from your initial post. “It just drops to idle while driving”.  I’m trying to imagine this happening. Driving down the road the transmission engaged, the rear wheels push the engine’s flywheel around.  The engine can’t really drop to an idle. Unless you mean the engine power dies. No response from the foot throttle? You coast to the side of the road and the engine just idles and won’t speed up on pushing the gas pedal? You hit the switch on your electric fuel pump, then things return to normal? It accelerates fine? 

[Doug&Deb]

Sorry Keith. What I experience is a loss of power. Turning on the electric pump gets it back quickly. I haven’t had to pull over yet. It’s a complete lack of throttle response. I should have been more clear in my original post. 

[Doug&Deb]

Another update. I drove to work today with ambient temperature in the low 50’s. Got almost to work before it acted up. It’s weird. It seems like the pump is sucking air but it took 16 miles to show up. I would think a leak in the line would cause problems all the time.

[keithb7]

Is it possible that the in-line electric fuel pump that you installed, when not on, is creating an obstruction for the mechanical fuel pump? Letting fuel through but not quite enough that the engine needs?  When you hit the switch on the electric pump it refills the lines, mechanical pump and bowl quickly? 
 

Try going for a drive and turning on the electric pump switch about every 2-3 miniutes for a duration of about 3-5 seconds.  Do this for a few trips. Does the problem appear or not?

[Doug&Deb]

Keith I have an Airtex E-8902 pump that’s been on for several years now. I think it’s the same one you have on your Plymouth. It’s possible it’s causing the problem but I doubt it. 

[TodFitch]

Is there a hose section on the fuel line leading to the fuel pump on your '52? Generally there is somewhere so that there can be some flex between the engine and the frame.

 

If so, what is the age and condition? If the one on the car is original it is almost guaranteed to be degraded by modern gas. I’ve seen some where the rubber inside swelled due to modern gas additives to the point where very little fuel can get through. Or it might be cracking and starting to leak when under suction but maybe not pressure.

[Doug&Deb]

Tod, it’s new fuel injection hose which is better quality than standard fuel hose. 

[Los_Control]

1 hour ago, Doug&Deb said:

Tod, it’s new fuel injection hose which is better quality than standard fuel hose. 

That is good stuff and since it is a few years old, what I think I know is your complete fuel system has been replaced and working for a few years.

 

It all seems to come back to, if you use the electric pump the problem goes away.

New fuel tank, new lines,  new pump ...... I would be tempted to say your fuel pump is failing when it gets warm?

 

Is it a rebuilt pump, is it possible it has a crack in it somewhere ..... hard to introduce air bubbles if there is no leaks.

Is it possible your pump just stopped working and was just some sort of turbulence you saw?

It is possible you may have a joint or connection not quite tight enough in your fuel lines ..... I just doubt this if no areas are wet to the touch.

 

Only thing I can think of, your mechanical pump is failing when it gets warmed up or working intermittently off & on ..... the electric pump saves your bacon.

With today's modern crap they sell as replacement parts, I can not imagine what is failing ...... seems everything works fine except the mechanical pump.

 

I picked up my pump at Napa ..... seems it was pretty painless at $35 or so, might be worth a shot to just replace the one you have.

Edited July 1 by Los_Control

[Doug&Deb]

Los I think it’s the mechanical pump also. It’s a new one but I think it’s cracked somewhere and heat is causing the crack to open enough to cause problems. I found two older pumps in my parts stash. I’m planning on rebuilding one and trying that. If that doesn’t work I may just go with an electric pump and eliminate the mechanical pump altogether.

[9 foot box]

   Check the vented gas cap. The button can stick from humidity in the filler neck. It’s been awhile since anyone has mentioned it, but it happens. 

[Dan Hiebert]

FWIW, what Kieth (in Canada) describes in that last post is what was happening with our daughter's '63 Falcon (yeah, yeah, not the right car, but same context). I had installed an electric fuel pump close to the fuel tank and kept the mechanical fuel pump.  Car ran fine for a few years then experienced the same problems Doug&Deb are having.  In this case, the electric pump was kind of self destructing, something breaking up in the pump clogged the system just enough that the mechanical pump couldn't keep up by itself.  Removed the electric pump and had to replace the mechanical one (the fuel pump for that model Ford, 144ci I6, has an integral fuel filter that can't be serviced).  So, not the electric fuel pump itself per se, but obstruction in the system that the mechanical one couldn't get past.  I'm thinking that may cause the mechanical one to work all that much harder and "find" leaks (hence the bubbles) that are otherwise undetectable.  Just a thought.  

[Sniper]

8 hours ago, 9 foot box said:

   Check the vented gas cap. The button can stick from humidity in the filler neck. It’s been awhile since anyone has mentioned it, but it happens. 

 

Good point here, the original cap was just open, replacement caps do have the button issue mentioned.  Ran into an issue where the cap I had on the car when I bought it would not vent properly causing he gas tank to oil can.

 

I thought I had a write up on it, anyway here's a thread with details on the vent issue.

 

 

 

[DPCD1941]

I am having the same problem but without the Electric fuel pump. It is on a 1941 WC with the 230 engine. I have tried new distributor, points, condenser and rebuilt Carburetor. New Fuel lines and cleaned the pump and inline filter. I can Idle for an hour no issues. But if I drive a mile down the road I start sputtering and die. Then wait a couple mins and it will start up and drive 200-400 feet sputter and die. Over and over. After it dies I still have fuel to the carb and I can pump the gas and rev it as it dies. I can only assume it has to be a spark issue. The temperature outside doesn’t affect it either. The most frustrating part is I can’t replicate it in the driveway. so every time I try an adjustment I have to leave, break down, call the wife and get towed back home. I am at my wits end. The only thing left to replace is the coil and it should be here tomorrow. 

Edited July 2 by DPCD1941