Okay I posted on my problems with this engine two-three weeks ago. It went from running crappy, dieseling, and not running, to running poorly and no charge. I finally gave up after doing all the following with no positive results. I brought it down to my local wrench turners ( good rep ) last Thursday. They have yet to look at it. I got to thinking aside from the charging system, Could my running problem / dieseling be related to a bad cam?


So many variables I'm lost.

I feel like a liberal. I'm just throwing money at the problem and it isn't getting any better!!! LOL!!!!

1972 Ford F250

Engine: 428
Trans: C-6
Carb: Carter AFB competition Series 600-625 cfm
Mallory Unilite electronic ignition system
Coil MSD II BLASTER
Wiring harness: Whacked

To the Mechanic(s)

History: I bought the truck last June and two things bothered me about it which I tried to address this past March. Coincidentally? this is when it began dieseling at shut down, and started bogging more with aggressive acceleration or load, and ultimately resulted in where it is now.

The two things:
1.Very high idle
2.Bogged down when I dumped the pedal.

Initially I thought Carb but no improvement with any adjustment I made.
I put the timing light on her and she was advanced. How much I don't know ( guessing 10 -12 deg's. ). I backed the timing off to the mark and she idled more in keeping with a big block but now she was a dog and she started dieseling on me shortly after whenever I shut her down after heating up.( Wouldn't diesel when cold ).

I advanced the timing to about 5 deg. and she ran somewhat better but the dieseling continued. Reset the carb adjustments back to the original points ( two screws on front ) and set timing back to approximately the original point. High idle returned but she still continued to diesel at shut down after heating up? WTF???

So I set her back to about 5 deg advance and ran her like that until the problems below started.


These problems started about a month ago.

First, she started bogging and dying on me as I drove down the road, Typically under acceleration. She would make a wheezing sucking sound and no pedal would be the result with the engine dieseling before it died.Finally she wouldn't even run, weak spark. but fuel was showing in the filter.

Initially I thought it was the fuel system. So I did the following:

1. Checked all lines from fuel pump to carb
2. Changed in line fuel filter
3. Replaced fuel pump
4. Replace vacuum hoses
5. check for vacuum leaks

No change. Research led me to ignition module potential failure ( similar symptoms ) ( a little knowledge is dangerous LOL!!!! )
1. Replaced ignition module
2. Replaced coil ( MSD II Blaster )
3. Cleaned plugs ( good condition )
4. Checked cap and rotor ( looked okay )

Started up ran for a couple minutes died
Wouldn't start again. Poured gas into carb
Started, ran briefly. Repeated 3 times same result.

Back to fuel system.
1. Pull inline filter run direct line from pump to carb
2. Notice fuel tank switch beside seat. Rotate tank selector switch from main to aux tank several times. ( Frustrated )
3. Attempt start. She fires up and I let her run for about five minutes, Shut her down.
4. Reattach fuel filter.
5. Start again and let run about fifteen minutes. So, apparently a clog in the fuel tank switch?
6. Shut her down and she diesels.
7. Put her in reverse and shut her down. No diesel.

No improvement in performance. Still bogs badly unless I shift manually and I still need to be gentle on pedal.

More research, Potential weak spark?
Take it down to Advanced Auto and have charging system checked.
1. Battery checks bad. Won't even crank after I get her down there
2. Jump battery. No go
3. Replace battery
4. Check alternator, no charge
5. Replace alternator
6.I cleaned all my connections and grounds I could find.
7. Replaced starter solenoid ( when cleaning connections )

NOTE: Old alternator ( single wire ) has aftermarket voltage regulator bolted on it. It also has OEM voltage regulator still connected to wiring harness ( WTF? )

So I replace both voltage regulators as well. Take it down for a charging test. Still no charge. I'm lost.

What I want done is a diagnosis of why it is not charging. Determine if this is the root of why it is running so poorly ( breaks up under load / aggressive pedal ) due to weak spark? Or is this a carburetor issue? or both?

If it is something you deem I can fix please let me know what is needed and what I need to do ( I am trying to save money )
If you feel it is something which you would be better off doing then I will follow that advice as well.

FYI: I believe I read somewhere in my research that with the Mallory ignition 10-12 deg. advance is beneficial?If so, how do you set idle?
Also, that needing to run rich is a symptom of weak spark and now she runs best with about 1/2 to 3/4 choke when warmed up.
So, she has always run rich but now it's even more pronounced.
I only run mid grade or premium with octane booster in her.
The white mark on the vacuum port on the dizzy and A/C bracket are where the timing was when I bought her ( when lined up ).

When I got her I took her to Bundy's and had the compression tested and new plugs thrown in. Test results: 160-165 across the cylinders. Not great, but consistent.

 

Bogging could be cam related but, I'm really thinging a couple of things here....

1. poor/contaminated fuel? (this would also cause dieseling on shut-down)

2. Ignition advance is not right- somehow being too advanced and not coming down quick enough creating both the bog & dieseling).

3. vacume leak (carb)

4. Cam/crank timing, might have jumped a tooth on the chain, creating an overly retarded timing- bogging and dieseling

 

1,3,& 4 are the possibles. I am pretty positive about vacuum leaks not being an issue now. Been through at least two tanks of gas from different stations so 1 is likely out.

Hopefully when the shop looks at it they can confirm 2 or 4 or eliminate them. cosidering how hard she backfiered a couple of times I wouldn't be surprised finding the chain jumped.

While I probably didn't use the best systematic approach in my trouble shooting it is really weird how things cascaded from what seemed like a fuel system issue, to ignition, to fuel, to charging system malfunction.

I mean seriously. Gotta love old trucks! Especially if they aren't original. LOL

 

Give me a call and I'll help you out!!! 541-882-5177 Ask for Wes

 

Sometimes especially when things have been modded that you haven't done yourself, it's better just to go through and eliminate what you suspect- and typically, a jumped timimg chain would be low on the list compared to other items that you have id'd.

 

Thanks Wes. Much appreciated. What is a good time to call PST?

 

Actually, I should have said 2 & 4 are possibles as far as mechanical possibilities. I still think the major issue is electrical.

 

I had basically the same thing, it turned out I had a vacuum leak at the intake, it sucked oil in, the oil turned to carbon, and it dieseled like a mother.

The high idle points to a vacuum leak. Do this:

Lock the tranny in 1st if it's an auto, or get rolling with a manual, leave it in 2nd gear, and then rev the engine out to 3000-3500 RPM. Let off the gas, let it coast until it's down to 1000 RPM or so, and then hit the gas again. Does it blow a big blue puff of smoke?

If so, the intake is leaking and sucking oil. The oil increases the compression ratio, either by just being oil, or burning and turning to carbon, and causes it to diesel.

Of course, it might not have anything to do with this, but it's worth a check.

After that, do a compression check, and post the numbers. If it's really REALLY high, that points to a cam that's not big enough for the engine's compression, or some other screw-up with the engine where the compression is through the roof causing the dieseling.

Both of these checks cost nothing except your time, or the mechanic's hourly labor.

Also, I would suggest you look at how the ignition is powered. If for some reason, the ignition is somehow getting power when the key is off, that'll kill the battery, AND might cause the dieseling.

 

Thanks Krewat. Like I said it's in the shop right now so I will take it up with the mechanic. Definitely worth testing.

I have the alternator wire hooked to the battery side of the solenoid. It was on the starter side ( I think ) originally. Which side is correct?

 

Now here's where it gets weird. The stock alternator for your truck should have a regulator on the fender-well. Not on the alternator. So that's definitely not the stock-type alternator.

Now, what wire are you referring to? The heavy wire coming from the alternator? It should be on the battery side of the starter solenoid. Logically, if the alternator is charging, it should feed the battery, not the starter

 

Bingo. Heavy wire from alternator to solenoid. It is on the starter side. And yes, it is weird because when I replaced the alternator it had an after market voltage regulator bolted to it. I replaced that as well and then I saw that the old voltage regulator was also still attached to the harness! I decided I wasn't going to change anything so I bought a new OEM voltage regualtor as well and replaced the old one.

So, to reiterate, It has a new battery, new alternator w/ after market voltage regulator, and new OEM voltage regulator. Like I said WHACKED!!!!

The only thing I can think of is whoever put in the Mallory ignition system replaced the alternator with one that had an external voltage regualtor on it? Or, was told he needed it ( external voltage regulator )?

The one thing I do know ( or 2-3 things ) is: the battery, alternator, and aftermarket and OEM voltage regualtors are all new and I'm not getting an effing charge!!!!

WTF
WHACKED!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

God!! I do so love my old truck though!!!! I'm sure once I have exhausted my bank account the problem will be resolved or, I will find a cliff and make a youtube moment.

 

anytime after 4pm (PST)!!! Give a shout out. Just too much to type, I would rather talk LOL.

 

Got her back from the shop last night.

Once the laughter dies down you can respond.

Okay, in a nutshell whoever put the Mallory ignition in or tuned it up last had no clue what they were doing and obviously neither did I. I can at least blame my inability on rustiness! LOL.

Anyway, the timing was way off and the distributor was set to full advance so any timing I tried to do was counter productive. The mechanic said something about changing the vacuum to port vacuum? I need to talk to him again ( I picked it up right as he was heading out and didn't want to keep him ). I have no idea what that means at the moment.

There was also a vacuum leak which I missed. Once he adjusted the dizzy, set the timing and fixed the vacuum leak...voila!!!

The biggest thing I noticed though is she doesn't have the get up and go she had from a dead start but she is running a hundred % better, purrs like a kitten at idle and runs real smooth, so overall I am not complaining. Just seems like she should have more poswer being that it is a 428.

It is charging but not as strong as it should be? He said it's putting out 13.5.

What is the norm???

 

The big wire from the alternator should go to the BATTERY side of the solenoid.

 

13.5 is fine.