What on earth could be causing this?

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Just a simple and quick way to check to see if it may be the fuel is getting to hot is to wrap the fuel line,( part that is close to the engine) With aluminum foil, leaving the foil bunched up and loose around the line. Old Drag racing trick.
 
Just an update. I took the car out today for a couple errands. Its very hot and humid out even in the shade but I drove it anyway. Did fine the first part of the trip. When I left the bank I was on a very busy road. I was in stop n go traffic and it started to surge like it was on the highway but this was driving 15-20mph. I pulled off into a parking lot then left and it did it again until I came to the next stop light then all was fine after that. When I left the next stop it did it again on a back road towards home. But not once did the car quit just surged real bad where I could not give it anymore gas unless I slowed down or came to a stop. This evening when its cooler out i'll check my vacuum hoses to make sure I don't have a leak. Also make sure my distributo is tight. I hope I find the issue becuase this is starting to get old already. I like the foil idea to keep the fuel cold but I have driven the car in weather like this before with no issues so something isnt right.

Thanks everyone
 
Sounds like you got some bad gas to me... I got some bad gas in my 97' jeep cherokee, sometimes it would run great then sometimes it acted like you was turning the switch off, I had to pull it's tank to get to it's fuel filter, changed the filter, cleaned the tank, put some good gas in and it never done it again..
 
greenhornet said:
Sounds like you got some bad gas to me... I got some bad gas in my 97' jeep cherokee, sometimes it would run great then sometimes it acted like you was turning the switch off, I had to pull it's tank to get to it's fuel filter, changed the filter, cleaned the tank, put some good gas in and it never done it again..
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I keep thinking this becuase I have never used UDF gas since the engine has been rebuilt. Almost always use BP. Is it that far fetched that bad gas could be causing this? It really is like an on off switch, very random and UDF is all thats currently in the tank.
 
7duster4 said:
I keep thinking this becuase I have never used UDF gas since the engine has been rebuilt. Almost always use BP. Is it that far fetched that bad gas could be causing this? It really is like an on off switch, very random and UDF is all thats currently in the tank.
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Bad gas I got at wal-mart (murphys) downed 3 cars for me in 2 weeks before I figured out what It was... thay ran fine some of the time then it was like thay were shutting down, like you turned the switch off, it was random.. if your coil and eletronic box is good I don't know what eles it could be...
 
Change out your coil!!! my brother and my self have both had a similar issue in hot weather, i spent weeks thinking it was a vapor lock/fuel issue. pulled the cheap chrome coil off, put on the factory black mopar coil and it runs perfect! super easy fix if its the same problem. good luck
 
The coil thats on it is one of those msd blaster coils. Less than a year old. Do these have a habit of causing issues in hot weather?
 
MSD coils either work or they don't. I am also suspect to bad gas....Surging is NOT a symptom of a vacuum leak. Fill up with hi octane BP, 76, Chevron.....see what happens.
 
If you got a bad batch of gas, it would run bad cold as well as hot so that's probably not the reason. Testing the coil while it's hot is easy enough for any competant shop to do. I still think it's a fuel delivery problem....VOLUME not pressure. A weak pump can cause fuel starvation under various conditons and change with temperature changes. One way to help diagnos the problem is to drive off while the car is stone cold, put the car in manual 1st, and put the pedal to the floor.(in a safe area to do so! Uphill would be even better) Bring the RPM's up to 4000 and leave it there for 10 seconds or so. If it will go that high, fuel delivery is probably ok but it still could be a faulty pump that acts up only when it warms up. This test will also eliminate the overheated coil likelyhood as the coil hasn't had time to heat up yet. I'm assuming you don't have any kind of rev limiter on the car right?
 
Now, it sounds so much like the problem I used to have with my slant six. This is how I knew what the issue was. Please pardon my rookie vocabulary but, the vacuum line that is on the distributor's "dish looking thing" unplug that, and see if it runs fine now. If that works you know that's the bad part. Worked for me, one morning going to school, though all was going to hell because I had to be on time for an exam and it happened just at that moment. Unplugged that, and it ran fine ever since, I do have to fix the cause though, hehe.
 
You might want to read over this thread because I had the same problem as you have now. There is alot of suggestions from the members on that thread.

http://www.forabodiesonly.com/mopar/showthread.php?t=59704&highlight=vapor+lock

Heat, trash in tank, and a crappy Carter fuel pump was my problem. It was a definite head scratcher but I got it fixed. I can drive it in hot weather all day long now.
 
Had a similar problem with my 79-300. Repalced the fuel pump as the old one failed. After that the car after it was warmed up and then shut down would do exactly the same thing. Couldn't get up to speed as the car was bucking kind of like it was runnimg out of fuel. Turns out they sold me a pump for a 2bbl engine but mine came with a 4. Got the right pump and runs great now.
 
7duster4 said:
The coil thats on it is one of those msd blaster coils. Less than a year old. Do these have a habit of causing issues in hot weather?
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dont have experience with the msd blaster specifically but seen multiple aftermarket coils not work in hot weather, if you have a spare coil around swap them out for a test. and never put a chrome accel coil on it! those are gauranteed to fail..good luck
 
BLOW-DART said:
dont have experience with the msd blaster specifically but seen multiple aftermarket coils not work in hot weather, if you have a spare coil around swap them out for a test. and never put a chrome accel coil on it! those are gauranteed to fail..good luck
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one evening this week i'll take it out and hammer on it while its cold and see what happens. So once its warm and if it starts to surge then the coil could be the issue? I don't happen to have an spare lying around but it could be giving me problems when its hot out. I think there is an old one ot my parents house.

If I do end up getting a fuel pump will this one work for my 5/16 fuel line?

http://www.summitracing.com/parts/SUM-250014-1/

The current pump is one of the cheap ones from any auto parts retailer. Its about 4 years old.
 
7duster4 said:
one evening this week i'll take it out and hammer on it while its cold and see what happens. So once its warm and if it starts to surge then the coil could be the issue? I don't happen to have an spare lying around but it could be giving me problems when its hot out. I think there is an old one ot my parents house.

If I do end up getting a fuel pump will this one work for my 5/16 fuel line?

http://www.summitracing.com/parts/SUM-250014-1/

The current pump is one of the cheap ones from any auto parts retailer. Its about 4 years old.
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You really need to tell us all of your engine modifications, we're kinda guessing in the dark here trying to help.. I personally think that the pump from summit is overkill.. You don't need 8 psi on a stock engine..
 
greenhornet said:
You really need to tell us all of your engine modifications, we're kinda guessing in the dark here trying to help.. I personally think that the pump from summit is overkill.. You don't need 8 psi on a stock engine..
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agreed on the fuel pump, the increased pressure will probably give you more problems then good.


I would find that coil at your parents and just swap it out, its a quick test to see if its your coil vs. fuel. and coils can work just great cold and horrible hot if its bad that is. good luck
 
greenhornet said:
You really need to tell us all of your engine modifications, we're kinda guessing in the dark here trying to help.. I personally think that the pump from summit is overkill.. You don't need 8 psi on a stock engine..
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Your probably right on the pump. My 318 is a mild build. 4-barrel with 340 cam and duels. Some head work on the stock heads but nothing much. Stock 904 with rebuild and 3.21 8 1/4 sure-grip.

Im hoping to drive it this evening if it dosn't rain. As soon as I get it on the road i'll punch it and see what happens with it not being fully warmed up.
 
Next time it does that, pull over immediately and open the fuel filler cap. If you here a "whoosh" the tank's venting is plugged. Get a vented cap or find the problem with the vent lines on the tank. I've had this happen twice. Once was a kink in the vent hose that came lose and drooped over time. The other was a helpful fellow who saw an open nipple on the tank and stuck a vacuum cap on it...
 
I vote on the fuel pump....especially if the old one is aftermarket or a rebuild.

I am having the same issues on my super bee right now and have checked everything except fuel pressure.....that's the next thing in line and I bet that's my problem........this has happened to me before....years ago and I finally fixed the problem with an electric fuel pump.....back in 80's the rebuilt ones from my local auto parts store were junk and the diaphram's would dry up if they sat over winter and/or did not get used all the time.....they would not go out all at once....just when they did you ended up with the same symptoms as you and I are experiencing right now.

Thus why I went with electric on that car and never had a problem again......until I blew a fuse that is:-D

I am getting a pressure gauge and a new pump for the bee and see if that finally remedies my problem....let us know what happens on your end.

Mop
 
An update:

I took the car for a drive this evening. Not once did it surge on me. Performed flawlessly. Figures when I am expecting it to act up on me it does perfect. I for sure got it up to tempurature. Even pulling away from lights nothing happened.

I was thinking about another possible symptom. Lately its been a real pain in the *** to start when cold. I would say the last month its been doing this. Seems fine when hot but after sitting for at least a day its a real annoyance to fire up. Used to be I would give it one pump and it would fire at the turn of the key. Now it just keeps cranking even while pumping. Cranking sounds fine not weak or anything. I'll stop for a minute thinking I flooded it then do it again. Usually it will fire up if not I keep trying. Could this be another sign of a bad fuel pump? coil?

As far as a vented gas cap. I beleive the one on it is vented and there is a tiny pinhole drilled out where the cap screws on. A buddy suggested that a few years ago when the engine was dropped back in. But if it does surge on me again I'll pull over and remove the cap.

Thanks everyone for the feedback. Starting to sound like the pump but im confused as to why nothing happened this evening while beating on it.
 
redfastback said:
If a metal filter is rusting, it has been in the car way too long. Metal ones are the safest. Ever seen a fire due to a plastic or glass filter?? I have.

If it's clogged you won't be able to blow thru it, a simple test.

You probably have vapor lock. Try getting a wood/plastic spacer for the carb.
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x2 and change METAL filter move away from heat source ie.intake ex. redfastback is 100% correct on all counts a non metal spacer under carb. esp. with a cast iron intake.this fixed my 74powerwagon it had the same thing going on.
 
I read through "mullinax95" thread and sure does sound like the exact same issues I am having. So as of now I am suspecting the fuel pump since its been so hard to start when cold. I will also change to a metal filter in the process of installing the new pump.

The only time I have ever done a fuel pump was on this engine when it was on a stand. That was a few years ago. When I take the old one out will the new one simply slide in to place? Or is there something else that needs to be done in order for that long arm to be where it needs to be?

As far as a spacer, right now I have two gaskets between the carb and intake. I really wanted to use a 1/2" spacer but I would have to cut a hole in my hood.

Thanks
 
I went ahead and purchased a new pump and a metal filter. Is there anything I should look for on the old pump to know its for sure the problem? Will the long arm be worn down in some way? Im assuming its a straight forward installation, just pull the old one out and the new one will slide into place?

thanks again for all the feedback
 
7duster4 said:
I went ahead and purchased a new pump and a metal filter. Is there anything I should look for on the old pump to know its for sure the problem? Will the long arm be worn down in some way? Im assuming its a straight forward installation, just pull the old one out and the new one will slide into place?

thanks again for all the feedback
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I think the diaphragm in the pump will go bad before the arm will wear out. My old Carter fuel pump would shoot gas out when I pushed the arm down but while the motor was running the fuel pressure would drop down to 4 psi. My new stock type fuel pump would keep the pressure between 6.5 and 8 psi. If you have some type of fuel pressure gauge in line some where would be a good idea. You don't HAVE to but I find in helpful to know how much pressure that I am getting to the carb.

I can't really tell you exactly what fixed the problem I was having but when I installed the Griffin radiator plus shroud the problem went away. The entire engine bay of the car would not heat up as much as it did with the stock radiator. The inside of the car is even cooler while traveling down the road.... it was amazing what a good radiator will do. The car quit running out of gas even though I had a full tank. LOL
 
do you run a MP electronic ignition? Is so..check the rear of the ECU for a 'hole' or 'blowout'. I don't know how to describe it really. But if you have either of my descriptions you will know. And always carry an extra ballast resister in the glove box. I don't believe the the MP electronic ignition is an off battery connection like an MSD. And any weakness in your existing wiring could cause a short or fault with the ECU. And would be hard to start..especially when its hot. Just something to check if it this turn out not be be fuel related.
 
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