At My Wits End With This Engine!

[73azbronco]

OK, do not start replacing parts yet.

What is the fuel pressure at the carb with the engine at idle? And when you rev it up? If you take the fuel line at the carb and place it in a bucket, with the engine cranking over (pull the dizzy coil wire to ground) does the fuel run freely and start to fill the bucket? Oh and be careful with fuel under pressure, do this with truck outside of garage. http://www.wikihow.com/Check-Your-Fuel-Pump

The crappiest carb on the planet will accelerate, you have other issues than a crappy carb, I think.

 

[lonesouth]

I suggested the carb because he said he recently rebuilt it. I've rebuilt a carb poorly before and had to do it again. Putting a known good carb on will at least eliminate it as a problem. If it were me, I'd find someone local with a carbed 302(truck/bronco/mustang/etc) that is running and see if you can swap parts to eliminate problem areas for a day.

 

[joshnjulie1]

yeah, I think these checks will be first on the list before replacing parts.
I am going to check the fuel pump, then put a regulator in-line.
Anyone recommend a good/reliabel fuel regulator I can get at the parts store?

 

[707Bronk]

Having a fuel pressure gauge just before the carb helps a lot to eliminate possible causes.

And if it seems like it just isn't getting full power, but otherwise running, it could be the secondaries aren't opening up properly. Even though they are vacuum secondaries, they still have to be initially mechanically set correctly.

X2 - lonesouth, I have rebuilt mine and it still ran like crap, and after fixing a lot of other things which didn't help, ended up rebuilding it again, and it finally fixed the problem.

 

[DuctTape]

Did you leave the key on without the engine running for any period of time?

I had a similar issue that I chased around for months. Turned out to be the pertronix module. I didn't know it at the time but if you give the module power without engine running the module can go funky and give really weird symptoms.

I got black plugs not from too rich but from inadequate combustion. I got the symptoms of a carb problem but it wasn't the carb. I changed jets and springs and rods to no avail.

I basically chased everything before I found it (thanks to a member's suggestion here). New module re-tune the carb and boom. Runs great now.

 

[joshnjulie1]

Here is the link to the fuel pump I have.
It shows an operating psi of 6.5

http://www.oreillyauto.com/site/c/d...&redirectkeyword=fuel+pump&pt=C0401&ppt=C0025

According to my carb manual,
If it is more than 6.0 psi at IDLE, it should be reduced
through the use of a regulator, such as Edelbrock #8190

Is 0.5psi really an issue???

 

[joshnjulie1]

"I had a similar issue that I chased around for months. Turned out to be the pertronix module. I didn't know it at the time but if you give the module power without engine running the module can go funky and give really weird symptoms."

Could be possible. I could replace with points to verify.

 

[joshnjulie1]

Pertronics Ignitor II should still be under warranty.
Think they will take it back if I tell them it is faulty?

 

[DuctTape]

Pertronics Ignitor II should still be under warranty.
Think they will take it back if I tell them it is faulty?

Dunno I didn't try. Figured it was my fault leaving key in run while fixing wiring.

I learned that if I have to troubleshoot wiring again d/c the module!

But, if you can get one from a local parts store you could try the swap to see and return it I suppose.

Don't forget that if you monkeyed with carb chasing it you may have to monkey with it again.

Sadly there is no way to bench test the module for erratic behavior. I did the only test available (according to pertronix) and that test said the module was good.

 

[75junebug]

I got mine from Oriellys, who have a No electrical parts return policy. I went thru 3 units with some very funky, non-consistant symptoms. Could have been my source 12v wire bieng from the original duraspark resistor wire....or not. I went HEI and solved all my issues.

 

[DirtDonk]

Did you keep your modules junebug? Might consider trying them out or selling them outright to people here, but with the stipulation that you're not sure what was up with them.
At least that's better than sitting around collecting dust, when you're no longer going to be using them. And since you could possibly have been under-volting them, it's possible they are perfectly good.

Your HEI is supposed to have full 12 volts too though. Did you run from a different wire when you finally made that swap?

Paul

 

[73azbronco]

A link to the fuel pump is not testing the output, what is the fuel pump pressure?

There are some basic tools you need, I think you can rent them for free from autozone and such. Fuel pressure gauge, vacuum guage (sometimes one in the same), timing light, dwell meter, step feeler gauges.

Lets eliminate one of the most common problems, fuel supply, before we go dive in and replace parts.

But even before that, have you pulled the plugs and done a cold compression check and looked at what the plugs look like?

After you know you have good fuel, then look to the dizzy side of the issue, since you are running a petronix system, I'll let those experts chime in. But go through this in a step by step and CHEAPEST way possible. I just want to tell you, Good luck, we are all counting on you.

http://www.youtube.com/watch?v=aB2yqeD0Nus

Based on what you are saying, I recommend you prove the fuel supply is good, then double check the distributor for proper operation, timing, it advances when revved, etc, then think about the carb.

 

[jckkys]

In your initial post you described an off idle bog or hesitation, after witch it takes off consistently. Now you say the engine isn't running correctly under any circumstances. It's not possible to diagnose a problem when the symptoms change as described.

 

[Hubba]

yeah, I think these checks will be first on the list before replacing parts.
I am going to check the fuel pump, then put a regulator in-line.
Anyone recommend a good/reliabel fuel regulator I can get at the parts store?

I have been told that the Mr. Gasket was junk, but that is what the local parts store had and it works great for me.

 

[DuctTape]

Based on what you are saying, I recommend you prove the fuel supply is good, then double check the distributor for proper operation, timing, it advances when revved, etc, then think about the carb.

As someone that started with the carb first I 100% agree that this is the RIGHT troubleshooting process.

 

[joshnjulie1]

Yeah, I think that is the smartest approach. Will update.

 

[75junebug]

No, Donk, I didnt keep them, but I did start carrying a set of points and condensors as a backup... until I tried the HEI dizzy...Yes, after reading up on voltage issues, I did use another KO 12V source. We did try the modules on my brothers 69, and they were toast, not even sutable for a paperweight

 

[DirtDonk]

Cool. Glad you tested them at least, instead of just tossing them first.
And yeah, they're really not heavy enough to use as paperweights. ;D

Paul