Engine Troubleshooting...dies while cruising.

[Louiepooch]

Help please on where to start troubleshooting. This is the 3rd time in the last 1000 miles that my Bronco has done this. The engine will quit while cruising. I'll pull over to the side of the road and try to restart. It will crank, start and then immediately die again. First time I got it towed and let it sit for a week or so but it eventually started and was totally fine for the next few 100 miles. Second time, after about 10 minutes of cranking, starting and dying, it finally started and ran normally and ran perfectly fine for another few hundred miles. Third time happened yesterday. Same exact thing....died while cruising...pull over....crank, start, dies. This time I tried until the battery ran low and then had it towed. One thing I noticed but not sure if matters to the troubleshooting.....all three times started with me really accelerating hard full throttle from a slow speed and then backing off and just cruising at a normal cruising speed. Anyway, thanks in advance for any help on where to get started. I have limited maintenance abilities so unless something simple I'll probably be bringing it to someone else. Just wanted to see if any one on here had some ideas or had this problem before. Thanks

some specs: rebuilt 351W, Holley 650 with mechanical secondaries built specifically for motor, ZF 5 speed transmission, Carter electric fuel pump, oil pressure safety switch, all new fuel lines, fuel tank and fuel filters at restoration about 9000 miles ago.

 

[gnpenning]

What type of new fuel line did you run?
How close to the exhaust and do you have headers, what type?

When it dies have you checked the carb for fuel?

Have you checked for spark?

Can you hear the fuel pump running with the key in the on position and does it sound different than when it's running correctly?

Just a few easy questions for starters.

 

[Louiepooch]

Thanks for the quick response. Seems the fuel pump is not running with key on. I have an electric fan that runs with the key in the same position so it was always too loud to hear if the pump was running. I always heard the Carter's were fairly bullet proof so never thought to disconnect the fan and listen....assumed it was something else. I just did that and don't hear the pump running. Although, yesterday, while I didn't visually check for fuel in the carb, we could smell plenty of it in engine compartment while cranking. Who knows, might have been something else. So, should I start with just replacing the pump? As far as your other questions....rubber fuel line from the tank to the fuel pump...stainless steel fuel lines along frame rail. Closest anything gets to exhaust is the actual pump at about 8 inches away (enough?) from a bend in the exhaust. Have the BCBroncos Ceramic Headers but seem sufficient distance from fuel line. Have not checked for spark and would have to read up on how to do that.

 

[Louiepooch]

I guess the other question is could it be the oil pressure safety switch? It is a Carter brand as well.....If it or a connection goes bad could it stop the pump from running? Don't know how that all works with each other.

 

[gnpenning]

Please do not replace anything before doing proper testing. New doesn't mean good in today's world.

2 things every bronco owner should have are a test light and DVOM. Neither has to be a high dollar, a $15 -20 meter and $5-6 test light will do everything you need (don't know current pricing?). Way cheaper than wasting money on parts. DVOM is what you should buy right now if you don't already have one.

At this point you don't know if the pump or sending unit are bad and quick voltage tests will tell you for sure, that is what you want to know. Yes the pressure switch needs to be connected to let power flow to pump.

You need to know if voltage is correct and at the correct times to both items. This needs to be done before anything else at this point.

We can walk you through setting up and using the meter if needed. Pictures help to see exactly what you have. Plenty of YouTube stuff as well. This is pretty simple, you got this.

 

[Louiepooch]

Thanks for the words of encouragement but I think you'll find I have a rather large learning curve to climb. I'll get another dumb question out of the way....So a bad sending unit just like the pressure switch can also cause the pump to not come? I don't have a digital voltmeter so I'll get one so I can start figuring this thing out. Thanks again for the help.

 

[Rustytruck]

You do not specify what ignition you have. if its points worry about the condenser and if mag pick up for electronic ignitic chec and ohmm check the mag pick-up. these 2 items can get hot and shut down and then cool down and work again at least for a little while. if you had a spark tester you can easily test this harbor freight sells a cheap one. gotta find out if its fuel or spark that is the culpret. have you checked battery voltage in the morning before first start , have you checked battery vooltage wgie running and again when it dies? have you check coil voltage with key on and again when the engine dies?

 

[Louiepooch]

Well, based on some local advice I decided to start simple and change the fuel filter. Started right up and stayed running....at idle anyway. Need to check it on the road in next few days. Hopefully that is all it was.....But thanks for responding and getting me started on the troubleshooting. And based on your advice I am definitely going to get some basic equipment for the next time something goes awry. Thanks again.

 

[kat]

I was going to mention new fuel filter. My 2 cents is to put a in line CLEAR fuel filter between your gas tank and electric fuel pump and another one under the hood before going to the carb. They are cheap and since they are clear you can actually see gas being pumped when key is on. Not to mention electric fuel pumps can get trash in them and stop spinning. If your pump quits whining, try giving it a little tap on the side with a wrench. Sometimes that will help.
I don't have a electric fan on mine but with my long tube headers its really hard to hear the electric pump while running. I have been having fuel delivery issues myself and have to get out and stick my head under Bronco to hear it whine.
As far as sending unit goes I don't THINK it will not make your electric fuel pump come on. Like you, mine is hooked to the key RUN side.
Also my 2 cents is take that Holley and sell it. Holley's are finicky and based on your statement 'large learning curve to climb' you might fine a good Edelbrock or a quadrojet might be an easier carb down the road for ya