I am now at my wits end and am once again turning to you guys for some help. I have an 84 dodge ram with a 318 in it that has been converted to electronic ignition and has ran wonderfully (after replacing the transmission) ever since. What its doing is this; It will run and drive great while putting around town, as soon as I drive it on the highway at higher RPM's, it will run about 10-15 (14 miles or so) minutes then start losing power before finally cutting out. I wait about 5 minutes and it starts right back up again (after pumping the throttle and turning the key about 20-30 seconds) and runs for another 10-15 minutes. If I let the motor cool all the way down, say 15-20 minutes of rest, I can drive around town all day long (till I get on the highway again). I have replaced the coil, ballast resistor, and ran a new metal fuel line (to make it look nicer). I have been thinking vapor lock (due to metal fuel line which is suspended about an inch above the block), maybe a weak mechanical pump (doubtful), or maybe the voltage regulator. Like I said, I have no idea and can't afford to just start replacing things. Any ideas to help push me in the right direction would be appreciated.

did you check the pick up in the tank? they will rust and get holes and when the fuel level drops it will suck air.

look at how much fuel you have when it acts up.

sounds like a clogged fuel filter also.

could be the ecu going out or a weak coil getting hot(you changed that though?)

look the fusable link wires over for the ign power,have seen the almost burt and get hot and lose power cool off restarts.

dont know what elect ign it was changed to but 84 would have already been ecu/elect dist.

I always run a points dist with pertronix conversion,by-passing the BR for a full 12volts to the coil...never had to mess with it after that.

could very well be a fuel pump going out also,look at it and see if the weep hole is leaking gas,check the oil to see if it smells like gas.

what carb does it have? does it have a built in filter or stone?

what gas cap does it have ? should have a vented cap,a non vented cap would build vac and fuel pump cant suck fuel.

R&R the VR and ecu and clean the part that grounds them/firewall together.

do you have ground straps on the Batt/engine/core support/firewall ??

what I come up with thinking about the symptoms you desribe

with Scratchy.. could be the pump but most likely the strainer/sock on the end of the fuel pickup is clogged.



Drop the tank, pull the sending unit out to see. Flus the tank at this time.

It has a new sending unit, but I didn't flush the tank before putting the new one in.

It has a brand new fuel filter, that was the first thing I thought of too and happened to have a new one in my garage.

New coil, but the ECU is a mopar performance (orange box) that's about 7 years old.

Haven't checked the fusible links, but will.

Fuel pump is not leaking fuel out of the weep hole (but I didn't think to check that before), oil does not smell like fuel either

It has an Edelbrock performer 600 cfm.

I'll check on the ECU and the VR, I re-ran a ground strap from the VR to the intake when I swapped the ignition when I was getting away from the lean-burn setup (like was done previously by factory?)

That definately gave me some things to check, But you don't think that the metal fuel line might be getting warm?

thank you very much, I'll re-post what works so maybe somebody else will have an easier go of it.

Sounds like what happened on my Stepson's RR. It had a mud dauber's nest on the end of the vent line. Next time it happens pop off the gas cap and listen foe a rush of air. If your cap is vented that shouldn't happen. To check fuel supply use a hand vacuum pump on the fuel line(not hose) at the pump using the brake bleeding adapter. It shouldn't take a lot to pull fuel. If not try at the sending unit. You can also block one end of the line and try to pull a vacuum at the other.
Ron

Sounds like a fuel supply problem. Make sure the tank vents are not blocked. If the tank can not vent it will build vacuum as you remove fuel from it until the pump can't pull anymore fuel.
It could also be an air leak in the fuel line before the pump. I had a split hose back by the fuel tank, and the pump would supply a small volume of fuel to where the engine would idle, but once underload / higher rpm it would run out of fuel.

My 84 did the same thing. I removed the "sock" on the end of the pickup and put a see-tru filter before pump. rans great.
Joe