Problem with 76 302

[leener6357]

Novice needs suggestions! 1976 Bronco with 302 starts and runs great for a few miles or few minutes. Runs so good and smooth you think "Wow, she's running great". Then she bogs down as if running out of gas. Could be just sitting or running 70 mph on interstate. When you pull over if you wait a few minutes she will start right back up but then only run a minute or so. Again like starved for fuel. Replaced fuel filter and pump but obviously didn't need to as problem persists. Could this be related to getting up to a certain temp. What should I try next. Any suggestions?

 

[broncnaz]

Try replacing the ignition module sounds like its getting ready to go. Thats usually how it goes out once it warms up it kills the engine cool down again and it runs fine until it heats up again.

 

[Naildriver111]

Sounds like it's vapor locking like my 76 did. feel of the steel fuel line going to the carb, if it's too hot to hold on to then vapor locking is the problem. You can put a phenolic spacer between the fuel pump and block and that should fix it, I added an electric fuel pump and I know that fixed it

 

[gkling01]

I had same problem w/ my 76. changed the ignition module and problem solved. Maybe there is a way you can check it before replacing. good luck man.

 

[vap13]

I would also bet on the ignition module, same thing happend on my 76. I always keep a spare one with me because its not unusual.
Paul

 

[tml]

Ignition module... I tried several modules everyone of them caused the same issue. Got a Motorcraft module no problems so far. I noticed on the three I tried before the Motorcraft, the color combinations were the same but they came out of the module in a different alignment than the motorcraft.
Good luck

 

[leener6357]

Thanks guys. I suspected the ignition module but sense I had replaced it a couple of months ago I thought I might need to look elsewhere and didn't know where. Since it was the consensus and failure seems common (I didn't know), I replaced it yesterday (free thanks to the warranty) and test drove. It seems to be fixed. Maybe I should haul around a spare too! Thanks for the input. I'll let you know if it holds up.

 

[leener6357]

Bad news. Drive to work in the AM and she ran like a champ (75 degrees). Went to lunch she boggged down within 1 mile (95 degrees). Drove home in the PM (75 degrees) she ran like a champ. Does it sound like NAILDRIVER111 may be right with vapor lock???

 

[broncnaz]

Sounds like thats probably it but at least you know its not the module and now its new. Its never a bad idea to carry a spare module there cheap while they do go out its not always the case as you've found out. You might try loosely wrapping the fuel line with aluminum foil to see if it make any differance that practically free if it does then you've found your problem. You may also want to check your gas caps the vents may have become plugged try removing the caps next time it dies on you does it have any pressure when you remove it?

 

[vap13]

I would have lost a bet on that, the vents and caps as suggested is a good place to start. Have you changed the location or routing of any of the fuel lines, added headers?
Paul

 

[rustbucket]

If all else fails, try replacing the coil. They can heat up and cause the same type of problems.

 

[Naildriver111]

If you do have pressure release when removing the cap, check the vent hose on the fuel tank, it will come up the firewall on the passenger side and plug into the black canister (if you still have that too). To check it, remove 1 cap at a time (assuming there are 2 tanks) pull the hose loose and blow in it. There will be some resistance but air should go through it. If it is stopped up, I recommed changing all of the vent hose (about $4 worth) or you can simply unplug it from the tank and blow pressurized air through it.The vent tube was stopped up on my aux tank, and you don't have to remove the tank to repair that.

 

[taxx]

Sounds like it's vapor locking like my 76 did. feel of the steel fuel line going to the carb, if it's too hot to hold on to then vapor locking is the problem. You can put a phenolic spacer between the fuel pump and block and that should fix it, I added an electric fuel pump and I know that fixed it

Where did you get your spacer?

 

[Naildriver111]

I didn't use a spacer, decided to go with electric fuel pump instead. But I did see some at summitracing.com

 

[leener6357]

As for the phenolic spacer, how does that work? Installing the fuel pump was a real pain to get lined up. How does a "spacer" effect this? Only one gas tank here, so I'll check the vent tubing. I will probably try the coil also because it's older and easier and couldn't hurt, right? I do have headers on the 302 but they have been on a while and this problem just started.

 

[taxx]

As for the phenolic spacer, how does that work? Installing the fuel pump was a real pain to get lined up. How does a "spacer" effect this? Only one gas tank here, so I'll check the vent tubing. I will probably try the coil also because it's older and easier and couldn't hurt, right? I do have headers on the 302 but they have been on a while and this problem just started.

What I found was I was having this problem on the trail. There wasn't enough air movement to keep everything cooled off. Now I don't know if it is at my pump or at my carb, but I found running with the hood off greatly increased my performance. Therefore that tells me if you can increase the airflow under the hood the problem will go away. Spacers are cheaper so that might be a place to start, but next I would look at my fan and cooling system. Do you know what temp your engine is running at?

 

[Hazegray]

Those spacers work great in keeping your carb cool (I picked mine up from AutoZone), but I suspect they won't fix a vapor lock situation in the fuel lines.

What about your coil?

 

[Naildriver111]

As for the phenolic spacer, how does that work? Installing the fuel pump was a real pain to get lined up. How does a "spacer" effect this? Only one gas tank here, so I'll check the vent tubing. I will probably try the coil also because it's older and easier and couldn't hurt, right? I do have headers on the 302 but they have been on a while and this problem just started.

The spacer keeps the heat from transfering from the engine to the fuel pump, but I don't think it would have helped in my situation because I bought a cheap fuel pump from Advance auto parts. I think the cheap pumps overheat from the friction generated inside them.
Mine would vapor lock at 180 degrees, and it only gets that high on very hot days. I first thought it was a stopped up fuel line because the clear fuel filter would be empty every time it happened. But thanks to the good folks on this forum, I/We got it and a lot of other things working.

 

[Hazegray]

Since the fuel pump is bolted to the timing chain cover and the flow is to the carb, I don't believe the carb spacer would help much to keep things cool in the pump. Does that make sense??

Either way, I added the carb spacer & you can definately tell the temperature difference btwn the intake manifold and the carb.

 

[trailpsycho]

Even at 95 degrees outside, there is not enough time within 1 mile of your starting point to develop vapor lock...IMO. I still think module. When mine went out, it took a while to finally die and sometimes it ran great and sometimes it would just die...I was 300 miles into a 500 mile trip and exiting the interstate and it just stopped like I had turned off the key when I hit the bottom of the ramp. A new module was installed and it has not recurred in 4 yrs. Good luck with your gremlin. If you take your coil in, they can test it at the parts houses...both of the AAs anyway. Again, good luck.