223 boggs in third at 45mph

m1e9r5c6

New member
Hi everyone, hope someone can help. I recently got my truck on the road and we went for a cruise down the highway for the first time this weekend. The truck is running great around town, idles smooth and pulls hard in fist and second all the way up to 4000 rpm however as soon as I shift into third at that speed the engine will stumble and die. Let off a bit and it picks back up again. It has lots of power below that but hits a wall at 75kph. If I accelerate real gentle I can get up to and cruise at 80kph. Thought it was fuel pump or regulator but I checked both. Pump is putting out about 5.5 psi, and the regulator is set at about 3.0. Engine runs at 2100rpm at 80kph so I figure it should have a lot more to go.
56 F100 with a 223, Clifford intake/header, Weber 38/38 dges, 300 distributor conversion using GM HEI module and Ford TFI coil.
 
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Big six Farmer

Well-known member
Isnt 40 the top speed for a 223 ? 60 if you coast down a hill ?... Seriously, you need to check the fuel pump volume. Let the engine crank with the fuel line off into a can, measure how much in a time frame. There is a test for that, and specs. I cant tell you what the specs are, but it should be obvious if your not getting much fuel out of the line to the carb... I would say you have a weak fuel pump, or a restriction some where in the fuel line to it.
 

bubba22349

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Yes there should still be plenty left in a 223 that's in good condition. X2 yes testing fuel volume is good place to start. A few other things you could do. Have you checked or set the valve lash lately? Have you done a compression test? Do you have a full 12 volts of power going to the front of the ignition resistor with 6 to 7 volts on the other side? Whats the battery voltage at? Test the coils output & resistance, and do you have really good grounds going to the engine, frame, & body? Best of luck
 

m1e9r5c6

New member
Yes there us should still be plenty left in a 223 in good condition. X2 yes testing fuel volume is good place to start. A few other things you could do. Have you checked or set the valve lash lately? Have you done a compression test? Do you have a full 12 volts of power going to the front of the ignition resistor and 6 to 7 volts on the other side? Whats the battery voltage at? Test the coils output & resistance, and do you have really good grounds going to the engine, frame, & body? Best of luck
I didn’t think to check fuel volume output so I’ll give that a try. I am running an electric fuel pump instead of the mechanical one.
yes to testing everything else in that list. Compression is even and all the electrical checks out.
 

Soldmy66

Well-known member
Are all of the fuel lines rubber and, if so, are they new?

Is the fuel filter new?

Is the gas tank new or has it recently been cleaned?

Is sounds like a fuel restriction, at least it does "over the internet".

If so, it could be a collapsed hose on the suction side, or a filter that becomes clogged with sediment, but clear once the reduction in pressure allows the restriction to lesson.
 

Big six Farmer

Well-known member
If your filter is in fair shape, i would blow compressed air in the fuel line from where it connect to the Fuel pump. Blow back into the tank, with the fuel cap off. Then take it for a drive to see if it is better... The points Soldmy66 brings up are all possible, and need to be checked... You could have a very rusty fuel tank that is plugging up everything.
 

flatford6

Well-known member
Plugged fuel filter in the carb inlet fitting, junk in the inlet valve of the fuel pump, plugged fuel line or tank outlet fitting: not enough fuel flow!
 

Alastairq

Active member
The truck is trying to tell you something? It's old, possibly even ancient by today's standards.....and obviously doesn't want to frighten you? :)
What make/type of leccy fuel pump have you fitted?
 

m1e9r5c6

New member
Are all of the fuel lines rubber and, if so, are they new?

Is the fuel filter new?

Is the gas tank new or has it recently been cleaned?

Is sounds like a fuel restriction, at least it does "over the internet".

If so, it could be a collapsed hose on the suction side, or a filter that becomes clogged with sediment, but clear once the reduction in pressure allows the restriction to lesson.
Most of the fuel line is hard line except small lengths where connections to tank, filters, pump etc are.
I’m running two filters currently, at the tank and at the carb. I have tested without the one at the carb with the same results. Both are pretty new and the tank is brand new.
I did have junk in my carb at one point from a rusty hard line, hence the complete replacement of the fuel system from end to end. Also cleaned the card really well. This is also the reason I’m running a filter right at the carb to keep it as clean as possible.
 

m1e9r5c6

New member
Plugged fuel filter in the carb inlet fitting, junk in the inlet valve of the fuel pump, plugged fuel line or tank outlet fitting: not enough fuel flow!
I think I would agree, seems like she’s not getting enough fuel to keep up. Question is where is the restriction.
 

m1e9r5c6

New member
The truck is trying to tell you something? It's old, possibly even ancient by today's standards.....and obviously doesn't want to frighten you? :)
What make/type of leccy fuel pump have you fitted?
Good question on the fuel pump. Bought it years ago. No name or model on it and seems to be universal. I don’t even remember the flow or pressure specs. I did get a new pump that is supposed to be a 5-9 psi so maybe I’ll try swapping it in. Too bad the weather is too crappy here for another test drive. I’ll have to wait a bit.
 

m1e9r5c6

New member
Plugged fuel filter in the carb inlet fitting, junk in the inlet valve of the fuel pump, plugged fuel line or tank outlet fitting: not enough fuel flow!
Checked the carb filter right in the Webber and it is clean. One thing I am wondering is if air inlet restriction could be doing it. I’ve heard that maybe these Weber air filters are too small and restrictive.
 

bubba22349

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Great that fuel system is new and clean. So if the fuel tank and fuel lines are all new then you really shouldn't need a extra filter back at the tank that could make it harder for the fue pump to draw fuel with a rear mounted lower height fuel tank that some people install. However if your 1956 F100 is using the stock type in cab behind the seat fuel tank having that extra fuel filter won't hurt a thing Also Depending on were the fuel pump is located can make some difference, electric fuel pumps that are mounted closer to the fuel tank work better at pushing the fuel forward rather then they would at pulling it out of the tank from the front of the truck this again depends on the location of your fuel tank. Best of luck
 

Soldmy66

Well-known member
I've read that pumps need to be lower than the tank outlet leading to the pump so that they are fed by gravity; in other words they are a "pump", not a "suck". Just in case that applies.
 

Alastairq

Active member
Some makes of leccy pump are designed as 'suckers', some other s designed as 'pushers' or 'shovers.'
As a UK survivor, I can generally only relate to pumps available in the UK, but, the old SU type of electric pump is better sited in the engine bay as a puller, or sucker. Whereas the Facet type [solid state, looks like a wee box]...is definitely a pusher, so needs siting near to the tank, or below the tank bottom, height-wise. I am a Facet fan [not sure what they were called in the US market, I have one or two that originated in the US. [As in, were sold there]. Facet pumps come in a variety of pressure specs. The cheapest version usually pushes out up to 5 psi, which is enough for most float chambers. They need a pressure regulator if using bike carbs though. I know little about Aertex pumps, but suspect they are adequate for normal use. { Referring to Aertex in the UK amongst old farts means a type of vest that has millions of holes in it..the aertex vest!}
Can I suggest test driving, to create the problem, and immediately shutting off the motor and checking the level in the carb float chamber? That might give you an idea as to whether the engine is getting starved of fuel?

Does your carb have a choke? [For cold starting]. If a manual choke, then recreate the problem, and try pulling the choke out to give more fuel? [Only Czech Jikov carbs had a choke circuit without a flap over the top, so the driver could use the [manual] choke as a high speed enrichment device! Skodas, anyone?]

Is the dizzy giving full advance all the time?
 

m1e9r5c6

New member
Some makes of leccy pump are designed as 'suckers', some other s designed as 'pushers' or 'shovers.'
As a UK survivor, I can generally only relate to pumps available in the UK, but, the old SU type of electric pump is better sited in the engine bay as a puller, or sucker. Whereas the Facet type [solid state, looks like a wee box]...is definitely a pusher, so needs siting near to the tank, or below the tank bottom, height-wise. I am a Facet fan [not sure what they were called in the US market, I have one or two that originated in the US. [As in, were sold there]. Facet pumps come in a variety of pressure specs. The cheapest version usually pushes out up to 5 psi, which is enough for most float chambers. They need a pressure regulator if using bike carbs though. I know little about Aertex pumps, but suspect they are adequate for normal use. { Referring to Aertex in the UK amongst old farts means a type of vest that has millions of holes in it..the aertex vest!}
Can I suggest test driving, to create the problem, and immediately shutting off the motor and checking the level in the carb float chamber? That might give you an idea as to whether the engine is getting starved of fuel?

Does your carb have a choke? [For cold starting]. If a manual choke, then recreate the problem, and try pulling the choke out to give more fuel? [Only Czech Jikov carbs had a choke circuit without a flap over the top, so the driver could use the [manual] choke as a high speed enrichment device! Skodas, anyone?]

Is the dizzy giving full advance all the time?
E2B7EEFD-6128-4747-AB8A-7A6A6C88802C.jpegThis is the type of pump I have located at the rear of the truck right beside the tank. The tank is from a 66 mustang and has an outlet very near the bottom making it impossible to mount a pump below that level.
Not sure if you are familiar at all with Weber 38 DGES carbs but, you have to pull the top of the carb off to check the float level so that is also near impossible to do on the side of the road.
I guess I should confirm that the float level is in spec though. Thought I did when I cleaned it but you never know. Since it seems to be fuel related it doesn’t hurt to check.
 

m1e9r5c6

New member
Forgot to mention, I have timing set up at 15 initial, total is 35 at 2200 rpm. I know this is way more than ford spec but someone told me to give it as much as it likes at idle without pinging up a hill. She actually idles better at 20 initial but that would have given me way too much total timing.
 

pmuller9

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To really know if the fuel system is delivering enough fuel at WOT you should install a fuel pressure gauge to see if the pressure drops when the engine boggs.
If not then I would look at the main jets.
This is where an Air/Fuel ratio gauge really helps out.
 
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