1974 Other Ford Models Stutters/Stalls at higher RPM

Tiny
REVOLUTION0
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  • 1974 FORD
Engine Performance problem
1974 Other Ford Models 6 cyl Two Wheel Drive Automatic? Miles

This may be long: I have a 74 Ford Maverick (4.1L 250CI Single BBL - Mileage Unknown).
Here's the problem: After driving the car, my wife had to make a hard stop, which caused the car to nearly die. Since it drives rough, wants to die at higher RPM (say 2200+ although I have no tachometer so this may be off). I drove it, it ran fine until I reached about 50-55MPH. It stuttered but didn't die. It will still spin the wheels from a stop and has good response to throttle.
This is what I've repaired: MSD Blaster-2 Coil with Ballast Resister, Distributor rotor button, Fuel Filter, Carb. Rebuild kit - Reset float to OEM specs, spark plugs, plug wires, PCV valve, Battery and air filter. I'm nearly stumped, and REFUSE to give up (this is a proj. Car that I've invested $3K+ into already). I've purchased a fuel pump, but haven't installed it. Just would like your opinion as to what it might be or confirmation that I'm diagnosing correctly.
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Wednesday, April 16th, 2008 AT 12:10 PM

29 Replies

Tiny
MERLIN2021
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Does this one have points? Or Module? I would start by checking the dwell. Check at idle, then raise rpm to about 1500 rpm, dwell should remain constant. If not distributor shaft is worn. Also if it has trouble on deceleration, check the vacuum advance for binding and or leaking vacuum pot!
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Wednesday, April 16th, 2008 AT 12:19 PM
Tiny
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It is a point system. I will try to install the new fuel pump and reply with results. If it doesn't fix it, I'll do what you said and repair accordingly.

***EDIT*** by the way, Haven't had any trouble on decel. Just accelleration- when I was taking it home there is a upward hill. On that hill I had the throttle half floored and was at 30-35MPH (VERY slow for half floored) no knocking or noises. After the hill I pulled into the driveway fine, let it ilde (it idled like a dream) revved it - had great response and sounded fine.
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Wednesday, April 16th, 2008 AT 12:23 PM
Tiny
MERLIN2021
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Fuel pumps on these usually leak when they are no good. How confident are you about that carb rebuild? Anti stall dashpot adjusted right?
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Wednesday, April 16th, 2008 AT 12:27 PM
Tiny
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I haven't checked for leaks, since its carbureted the smell of gas coming from the hood doesn't get a second look from me. Although I have had to replace a gummed up fuel filter about 10-15 times within the 1.5 years of ownership. It, for some reason, gums up easy and reduces power and throttle response after just a month or so of driving, so I figure the 34 years of use for the fuel pump (it goes gas "tank - pump - filter - carb" on my car) may have some build up.

REPLY: Not too confident really. It was cheap and came with minimal parts. To be honest if the pump didn't fix it I was going to buy a whole new carb.
I'm no auto tech, in fact Im a computer tech. I just grew up around mechanics. If I'm correct, the antistall dashpot is located on the firewall-side of the carb with a baffle over the intake of the carb? If correct, there is nothing connected to it. I think someone may have altered it. I can physically move it with my finger though which acts like a choke (during cold weather, if I move it in the close position Idle becomes smoother).
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Wednesday, April 16th, 2008 AT 12:33 PM
Tiny
MERLIN2021
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The anti stall dashpot, is located at the throttle lever, it's the part where the end of the lever rests. On the throttle side towards the front.
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Wednesday, April 16th, 2008 AT 1:05 PM
Tiny
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In that case: no adjustments or servicing has occurred. If I remember correctly, the rebuild kit came with: gaskets, accellerator pump and diaphram, fuel inlet and a measurement tool for adjusting the float (but not the float itself). Nothing else came with the kit. Maybe worth noting: the fuel bowl had a fine, reddish sandlike substance at the bottom. Not enough to cover the bottom of the bowl, but enough to get me nervous.
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Wednesday, April 16th, 2008 AT 1:14 PM
Tiny
MERLIN2021
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When you do a do it yourself rebuild, you should get the right solvent and basket for doing them, and the carb should be dismantled and soaked for a good 6-8 hours, that will remove the varnish bilt up inside! The dashpot is sold seperatly. And I think 74's had no catalytic converters, so thier natural diet was leaded gas, so to run unleaded the valve seats need to be changed to hard seats! If not done the valves and seats will end up ruined.
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Wednesday, April 16th, 2008 AT 1:27 PM
Tiny
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I think I just died a little inside. You are correct, there is not catalytic converter (it's straight pipe). So do you think it's possible to drive with unleaded gas for all these years and just now experience the effects? What should I do?
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Wednesday, April 16th, 2008 AT 1:47 PM
Tiny
MERLIN2021
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No I believe this has been done already. Check the carb for the dashpot, and have a look at the timing and dwell.
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Wednesday, April 16th, 2008 AT 6:09 PM
Tiny
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Roger that. Thanks for the help. I know what to look for now.
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Wednesday, April 16th, 2008 AT 6:20 PM
Tiny
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So I got to looking. There is no antistall dashpot on my vehicle. Theres also no indication one was previously there/removed. Ill take that as less troubleshooting to do and try to find a dwell meter. Also I noticed there is some fluid (looks like oil maybe) that is or has leaked from the fuel pump. I don't think its gas since gas dries quickly. This stuff still looks a little wet. Ill consult someone to help me with the dwelling though since I'm not familiar with it.
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Wednesday, April 16th, 2008 AT 10:14 PM
Tiny
MERLIN2021
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You might want to pull the fuel pump line and test the volume, should be a pint in 30 seconds I think, afterall we are going way back on this one! Do you have a manual or at least the impotant specs for the car? Investigate the leak at the pump! Yes I know it's a Ford!
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Thursday, April 17th, 2008 AT 1:36 PM
Tiny
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These are some specs that may be important that I've found:

1974 Ford Maverick 250CI (4.1L) 1BBL Carbureted
Inline 6
Points distributor (Dwell Range: 35-39 Degrees)
Mechanical Fuel pump
Automatic C-4 Transmission with Ford Kickdown
No AC
With Power steering
MSD Blaster 2 Coil with Ballast Resistor
BWD Nascar Premium 7MM Plug wires
Autolite Platinum Plugs at.044 Gap
Fram Fuel filter (new as of 4 days ago)
Carter RBS carb - Single Barrel

Yeah, Investigating a leak in a 34 year old car ain't the easiest thing. Especially since it had a bad radiator about 6 months ago that destroyed nearly all the things I listed above from a huge leak. So nearly all stuff listed above is brand new. I still haven't been able to replace the Fuel Pump: I've inspected it, the difficulty for replacing it, making sure I know the ins and outs of replacing, but my job is interfering since I work during the daylight hours and have to carpool with my wife. Maybe I'll cut some hours off my shift today and get to replacing it and see what happens. :)

EDIT: BTW, someone said they think it is the fuel float since it runs fine at idle, low RPM but when gas demand is high it begins to shudder / die. I'll snap some pics of the distrib. And such today if I can and post the links.
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Friday, April 18th, 2008 AT 9:51 AM
Tiny
MERLIN2021
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Like I said that rebuild is questionable. Did you remove the needle valve and seat? Use a section of pipe cleaber to get what you can? All traces of carbon on the bottom plate. Etc. Etc.
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Friday, April 18th, 2008 AT 12:33 PM
Tiny
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Agreed- I'm not comfortable with the rebuild either. I replaced the needle and seat: there was no traces of obstruction (the passage is maybe 1/4 inches long). The problem is I never soaked the carb and I never dealt with carburetor rebuild before that: so I may have offset the float. I'm thinking I should take it into a shop for repair/rebuild. Should I consider other things too (other than replacing fuel pump)? I think you've narrowed it down pretty well. Just let me know what I should ask the mechanic to fix/look at if you would please. :)
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Friday, April 18th, 2008 AT 1:50 PM
Tiny
MERLIN2021
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Well you can check the condition of the points. Any pitting and they should be replaced, bad points usually give a bad idle, but not impossible to get your symtoms. If you apply vacuum to the advance, does it pull and release ok?
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Friday, April 18th, 2008 AT 1:56 PM
Tiny
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I don't have any way of testing vaccuum personally. I do however have some pictures I took today after replacing the fuel pump. I wasn't able to see if the fuel pump made things better (my upper radiator hose I bought doesn't fit.) I'm going to photoshop them and I'll post the links.
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Sunday, April 20th, 2008 AT 5:44 PM
Tiny
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http://www.2carpros.com/forum/automotive_pictures/179347_barrel_1.jpg



http://www.2carpros.com/forum/automotive_pictures/179347_broken_hose_1.jpg



http://www.2carpros.com/forum/automotive_pictures/179347_cap_1.jpg



http://www.2carpros.com/forum/automotive_pictures/179347_carb_1.jpg



http://www.2carpros.com/forum/automotive_pictures/179347_carb_sideview_1.jpg



http://www.2carpros.com/forum/automotive_pictures/179347_distrib_1.jpg



http://www.2carpros.com/forum/automotive_pictures/179347_distrib_topview_1.jpg



http://www.2carpros.com/forum/automotive_pictures/179347_old_pump_1.jpg



http://www.2carpros.com/forum/automotive_pictures/179347_pumpcoil_1.jpg



http://www.2carpros.com/forum/automotive_pictures/179347_rotor_button_1.jpg

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Sunday, April 20th, 2008 AT 6:18 PM
Tiny
MERLIN2021
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Choke thermostat is important, remove the 3 screws holding the bakelite cover on, an install the new spring. They used to make a replacemet tube for the exhaust, if you can't find one try plumbing supply, for a copper icemake line. I could not read the part about the plastic piece.
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Monday, April 21st, 2008 AT 2:24 AM
Tiny
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It said that the distributor rod is rounded where it meets the plastic piece (not edged) but does not appear to be worn. The plastic piece however does show signs of wear (little plastic fragments coming off). I'm just not sure what that "plastic piece" is called: Never worked with distributors- especially points systems. I've been thinking about just getting a conversion kit for electronic but I can't seem to locate one. They're all for Chevy V-8s it seems like. I'll fix that exhaust tube with some copper plumbing and maybe put some high-temp cold weld on it or something. By the way- that choke-looking-thing on the left of the carb in picture 4 looks like it has silicon all over the backside of it. There also is no spring there to move it: can the whole module be replaced? I don't know what the heck the previous owners were doing to this thing, but I don't much care for jimmy-rigging anything.

EDIT: I'm gonna go make a run to the performance parts store and try to order an electronic kit. If anyone in town can they can. I'll also see if they have the choke module.

EDIT2: Bought a new hose so I can test the car now. Bought a vacuum advance- it's on order. Figured it'd be better to spend the $20 dollars to replace it than the $70 dollars to buy a vacuum to test it. We should know how things are working by 3:00PM PST (my timezone). The ASE cert. Parts tech said if I could get it in driving order to stop back by to get the vaccuum lines checked and replaced. So I'll probably do that too.
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Monday, April 21st, 2008 AT 11:08 AM

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