Ok, here is the history. 1970 F100 302 2100 Carb 4SPD. I've had the truck for 2 years. The truck has run fine with no problems. About 2 months ago it started running really rough and had problems on acceleration. I noticed that the accelerator pump was leaking out of the weep hole. I replaced it. It ran fantastic after that. Leaving work one day about a month ago it stalled and died. I couldn't figure out why it wouldn't start then noticed I had no spark. I pulled the distributor cap grabbed a hold of the rotor and noticed that the rotor was spinning freely from side to side with much more play than originally designed I had snap the linkage at the VAC Advanced hooks to. I ordered a new distributor and installed it the following day finding top dead center on the compression stroke and with a timing light dialing it in. Upon getting it home I replaced spark plug wires and spark plugs I couldn't stop the truck at that point it ran beautifully. 2 weeks later we had hurricane Irma come through Florida. I have filled my truck up with fuel as a backup for my generator. After 4 days of the vehicle not driving and me robbing fuel for my generator it was time to go back to work I got in the truck fired it up and drove it to work I had no problems. After that point I started to have issues where I would be driving mainly at a cruise the engine would start to fall out I would disengage the clutch feather the throttle a little bit and it would come right back re-engage the clutch and continue on. Those symptoms to me told me that there had been water inside the tank. Three months prior I had put a new fuel tank in by the way. As the days progressed it got worse and worse and me thinking that I could just run the water out of it kept driving. At some point I made the decision that it wasn't going to get any better so I pulled off the air horn and sucked out the fuel that was in the bowl and found no water. I also disconnected the fuel line and filled up a bottle of water and found no water in the fuel. While the air horn was off and I had access to the float and Bowl I depressed the float and a very high pressure stream shot out of the needle and hit the hood. In my time dabbling with carburetors I know that they should not have that much pressure so I assumed there was maybe an issue with the fuel pump that it had gone faulty and was producing more pressure then Factory standard. So I purchased another and remove and replace the fuel pump. The new mechanical fuel pump worked great but still have the same amount of pressure that the first one had. So I purchased an inline pressure regulator one of those $30 mr. Gasket jobs and set it at 5 and a half PSI still I had the same problems but better pressure. I remove the carburetor when I received the rebuild kit that I purchased from GP Sorensen. I disassembled and cleaned and blew out all the Jets and ports and ensured that everything flowed well. I rebuilt the carburetor with all new parts that came in the kit ie new power valve, new accelerator pump, new float valve seat, new float needle, new gaskets Etc. I also redid All the settings according to the manual with the choke pull off, the butterfly spacing, choke thermostat, fast idle cam screw, accelerator pump linkage and the idle screws out at one and a half turns. I reinstalled the carburetor and hooked up the fuel and throttle linkages. Attempted to start it and of course it idles very rough. I then begin to get it to where it would idle long enough to warm up and begin my adjustments. I could not get it to accelerate whatsoever. I was able to dial it in just right with a good idle and good vacuum. But every time I gave it throttle it would stall. I began trying to find some reason why it would do that. I've search the web and I can't find the problem that I have. I began looking into vacuum leaks of all different kinds. I sprayed carb cleaner all around the base of the carb, the intake manifold gaskets, the vacuum trees, and brake booster. 0 vacuum leaks. I did however notice that the Riser plate under the carb was completely plugged up from the EGR hose. I remove the Riser plate and completely cleaned out the hose and the plate so that it was flowing freely and checked the EGR valve and it worked perfect. I reassembled and try it again. I still am having the same issue. I double-checked the accelerator pump to ensure that it was working properly and putting a nice dream at wide open which it does. When I disconnect the accelerator pump linkage and open the throttle I can get it to throttle up and it sounds nice. But when I reattach the accelerator pump linkage it sounds very throaty like it's getting too much fuel and bogs down and stalls. after I have tried that and restart the engine the vacuum pressure is weak and the engine idles very rough and acts like it wants to stall if I disconnect the linkage again and open it up wide open and let it snap back the RPMs ramp up well and the VAC pressure goes back to a higher number. Almost like it has fuel sitting in the intake and by allowing more air to flow through without dumping fuel cleans the side walls of the intake and brings the back pressure back up. Crazily no matter what kind or amount of fuel I put in that car it dies. If I so much as Spirits a little ether or carbon joke over the carburetor it will die or at the very least sputter and almost completely stall out. Even if I disconnect the accelerator pump linkage and open the throttle all the way while spraying carburetor cleaner into the air horn it will still bog stall and die. Here is a video showing my issue. Can someone please help me fix this as I have spoken to so many and have stumped the same amount.

 

Fuel leaking past accelerator pump?
Is the spring intact? Diaphram? The little red or black nipple thing properly seated?

Is the engine oil diluted with gasoline?

 

Tough one.
You have good vacuum at idle. When you hit it things go bad. When you do that you uncover the vacuum advance above the throttle plate and there is a transition from idle to power circuit in the carb.
So, I suggest you pull and plug all vacuum lines to the carb and try again.
Try sucking on the vacuum line to the distributor and see it it holds vacuum.
Report back. Stay with us.

 

if it was wouldnt it be leaking out of the weep hole? Its not. The red diaphram is new and installed with a bit of grease and properly seated. The spring is perfect. The oil seems legit. Doesnt smell of gasoline not seem thin.

 

I only have 1 Vac line at the carb. On the left side base. You want me to cap off all lines? I have 4 total. 1 to carb, 1 to distributor one to metered tree and one to brake booster. You want me to pull a vacuum on the distributor vac line to see if it holds vacuum? It would only make vacuum when i throttle it up. Which when i do the vacuum spikes on that line.

 

Welcome to FTE.
TRY backing off the dizzy or retard the timing. At 22 on the vacuum gauge you may be a little too far advanced. One bolt and 5 minutes....
I’m not saying it’s going to fix it but it seems like I’ve been here before.

 

Lol thanks for the welcome. ive been a member since 2015 Haha. I adjusted the dizzy several times. did you watch the vid? I adjusted it in the video. I had it advanced 7 degrees and dead on. Doesnt seem to work.

 

Does the distributor vacuum can hold? Remember at idle there won't be any extra advance pulled in, he is thinking maybe the diaphragm is busted and introducing a leak when goosing throttle.

Another thing you can check, is to see that the mechanical advance is working properly. Disconnect and plug vacuum advance port on carb and spool up the RPM. It should top out somewhere between 30° and 40° BTDC, but also looking for smooth advance and back down to base timing.

 

Headscratcher. I have a hunch.
:
The vacuum advance tube to the distributor may be hooked to full manifold vacuum, not above the throttle plate where it gets ported vacuum. This will give you full vacuum advance when you time at 7* at idle. When you hit the throttle, you will severely retard the spark and the squirts of fuel from the accelerator pump will flood the plugs.

So, cut about 1" of vacuum hose at the carb. Put a 10/24 screw in the short piece and reconnect it to the port. This blocks any vacuum reaching the advance unit and prevents air draw. Then retry.

I can't see where you have bit into for the T to the gauge.

I am flat out of ideas if your symptoms don't go away.

 

I feel like it’s in the iggy, which several comments refer. +20 hg on the dial is “usually” excessive. Is the point gap correct? Pertronix gap correct?

 

Seems to be. There is no vacuum on the line coming from the metered vacuum tee going to the vac advance until i throttle up. I will definitely try that with the distributor.

 

Its not hooked up to manifold vacuum. I have a line from manifold that feeds a metered tree (factory) and then feeds the carb and vac advance. (Btw its nice to know Im not the only one who makes plugs with 10-32 or 10-24 bolts haha)

 

idk about the point gaps. Ill have to read up on that. I REALLY dont think its the ignition. If i mist the tinyest bit of carb cleaner or starter fluid the RPMs dont spike. It just stalls. That CANT be an ignition issue.

 

Right, but what you want to determine here is whether or not the vacuum diaphragm inside the can is defective. The engine will always produce vacuum, but if the vacuum advance is defective it's going to simply be seen as a big vacuum leak at anything above idle. Not saying this is the problem but it should be checked.

 

While I didn't read your whole first post - my old eyes can't decipher one humongously long paragraph (some spacing here would help), I watched yer video and read the other members suggestions.

It seems you're not getting much help from the vacuum advance when you goose it. Pull the distributor cap....the rotor....check to see if the breaker plate moves freely (by hand...or finger) and the wires are not brittle/frayed....and the plate moves when suction is applied to the vacuum advance can - watch the arm and plate.

Troubleshooting 101.