my bronco will not run right

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powderman12345

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i have 1984 bronco with a brand new 351m in it i rebuilt the motor 5 years ago it has less than 200 miles on it. i tryed the whole fitech thing got frustated and took it off put a brand new holley on it the pomblm i having is when it warm it will not stay running loads up act like it has vacuum leak which i did check all of that when i did the break in and when i put the fitech on bascliy anytime i do any carb work on a motor i have check and replaced all the vuccum lines new fuel pump which im thinking about switching to electric. but it also the fuel filter is not staying full after it shut off im starting to think i have a fuel issues some where. but the also the filler neck is loose on the tank would that cause a issue like this also? also there is what i assume a return line that runs up the passager side of the frame from the tank to motor bay i have never had that hook up to anything for has long as i have had the bronco which as been since i was 16 im 33 now. can someone help.


p.s im not drunk or anything i just dont know how to spell all that well
 
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Hey there, hmmm. (yeah i'm not a big fan of the FiTec stuff either...)

Well the filler neck should not be an issue.

We are sure the mechanical condition of the engine is good? if you put on a vacuum gauge does it show steady vac and not jumpy like a overtightened/leaking intake valve? just checking. an oversight could have been why the FItec setup didn't work out. checking all angles here haha.

Did you abandon the mechanical fuel pump for an electric pump for the FItec setup? those need like 40PSI to run, whereas the carb is less than 5... going back to the previously abandoned mechanical pump, perhaps it's no longer good anymore if it were sucking road dirt etc for 200 miles..

A trick i do to test mechanical pumps is attach a longer hose (like 4') to the outlet of the pump, or hard line to carb (use a clamp, don't want it popping off) and aim the hose into a catch container. you have a friend crank the engine while you put your thumb over the end (aiming away from your face) you should be able to feel pressure build. 4psi will build up enough to push past your thumb fairly easily and into the catch container. if you feel you can very easily obstruct the flow, the diaphram may be ruptured, leaking internally to the crankcase, or the one way 'reed valves' no longer seal well.

Hows the choke setup responding? your in spokane, so def cold out. choke should close near completely when cold, and fast idle cam near fully engaged. After running for like 3 minutes, the choke thermostat's bimetal spring should relax and let the fast idle cam fall off a tooth to a lower idle setting.

is the choke falling open too quickly? and/or when it does, is the curb idle ***** set too low? perhaps watching the choke assembly as the engine warms up may provide more insight. Does the engine idle easily if you hold the throttle, or does it need to be 'goosed' and otherwise only runs over say 2500 rpm? if so this would indicate a possible lean condition with the idle circuit, or due to an air induction issue...

does seem like a fuel delivery issue of some sort...
 

Tiha

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You said loading up like flooding out?
Did you adjust the idle mixture screws?

Re set the float levels?
 
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powderman12345

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Hey there, hmmm. (yeah i'm not a big fan of the FiTec stuff either...)

Well the filler neck should not be an issue.

We are sure the mechanical condition of the engine is good? if you put on a vacuum gauge does it show steady vac and not jumpy like a overtightened/leaking intake valve? just checking. an oversight could have been why the FItec setup didn't work out. checking all angles here haha.

Did you abandon the mechanical fuel pump for an electric pump for the FItec setup? those need like 40PSI to run, whereas the carb is less than 5... going back to the previously abandoned mechanical pump, perhaps it's no longer good anymore if it were sucking road dirt etc for 200 miles..

A trick i do to test mechanical pumps is attach a longer hose (like 4') to the outlet of the pump, or hard line to carb (use a clamp, don't want it popping off) and aim the hose into a catch container. you have a friend crank the engine while you put your thumb over the end (aiming away from your face) you should be able to feel pressure build. 4psi will build up enough to push past your thumb fairly easily and into the catch container. if you feel you can very easily obstruct the flow, the diaphram may be ruptured, leaking internally to the crankcase, or the one way 'reed valves' no longer seal well.

Hows the choke setup responding? your in spokane, so def cold out. choke should close near completely when cold, and fast idle cam near fully engaged. After running for like 3 minutes, the choke thermostat's bimetal spring should relax and let the fast idle cam fall off a tooth to a lower idle setting.

is the choke falling open too quickly? and/or when it does, is the curb idle ***** set too low? perhaps watching the choke assembly as the engine warms up may provide more insight. Does the engine idle easily if you hold the throttle, or does it need to be 'goosed' and otherwise only runs over say 2500 rpm? if so this would indicate a possible lean condition with the idle circuit, or due to an air induction issue...

does seem like a fuel delivery issue of some sort...

hi thanks for the replay the motor is setup right i have built many motors over the year and take no shortcut when it come to motor builds

the fitech set up i made the mistake of useing fitech fuel command center which the mechanical pump could not keep up with the fuel command center but the mechanical pump is brand new i put it on when i built the motor.

so after i wrote this post i went out and pulled the tank because i need new one to correct the broken filler neck on the tank and found out the fuel hose coming out of the tank is very soft and coming apart inside so now im think that hose was closing off at a idil and not allowing fuel to come though intill i rev it up demanding more fuel than the line would stay open

btw im looking for a good tank if u know anyone that has one for sale i will pay shipping

and i havent been able to get it to run long enough to do any fine tuning the maybe 200 miles comment was and is probly a high number because i havent been able to get it to run long enough to do any long trips with it trying die or anything than it has sat for three four years do to my job i handle exploves so my job is really demanding at times

You said loading up like flooding out?
Did you adjust the idle mixture screws?

Re set the float levels?



Hey there, hmmm. (yeah i'm not a big fan of the FiTec stuff either...)

Well the filler neck should not be an issue.

We are sure the mechanical condition of the engine is good? if you put on a vacuum gauge does it show steady vac and not jumpy like a overtightened/leaking intake valve? just checking. an oversight could have been why the FItec setup didn't work out. checking all angles here haha.

Did you abandon the mechanical fuel pump for an electric pump for the FItec setup? those need like 40PSI to run, whereas the carb is less than 5... going back to the previously abandoned mechanical pump, perhaps it's no longer good anymore if it were sucking road dirt etc for 200 miles..

A trick i do to test mechanical pumps is attach a longer hose (like 4') to the outlet of the pump, or hard line to carb (use a clamp, don't want it popping off) and aim the hose into a catch container. you have a friend crank the engine while you put your thumb over the end (aiming away from your face) you should be able to feel pressure build. 4psi will build up enough to push past your thumb fairly easily and into the catch container. if you feel you can very easily obstruct the flow, the diaphram may be ruptured, leaking internally to the crankcase, or the one way 'reed valves' no longer seal well.

Hows the choke setup responding? your in spokane, so def cold out. choke should close near completely when cold, and fast idle cam near fully engaged. After running for like 3 minutes, the choke thermostat's bimetal spring should relax and let the fast idle cam fall off a tooth to a lower idle setting.

is the choke falling open too quickly? and/or when it does, is the curb idle ***** set too low? perhaps watching the choke assembly as the engine warms up may provide more insight. Does the engine idle easily if you hold the throttle, or does it need to be 'goosed' and otherwise only runs over say 2500 rpm? if so this would indicate a possible lean condition with the idle circuit, or due to an air induction issue...

does seem like a fuel delivery issue of some sort...
 
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powderman12345

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You said loading up like flooding out?
Did you adjust the idle mixture screws?

Re set the float levels?
hi thanks for the replay i havent been able to get it to run long enough to do any fine tuning now when i did put the new carb on i di in fact set the floats levels and mixture screws than drove it home from my grandpas it ran great than went to start it up and drive it somewhere and starting running like shit so i got mad and park the damn thing i replayed to one post on here about the fuel line coming out of the tank and how it really soft and coming apart in side so im thinking the line is closing off and now im hoping there not a chunk of rubber in my carb which yes i have a filter on there. but once i get a new tank and put a new rubber line and see if it will run i will go though and recheck all my carb adjustments. and the loading up i posted may have not been the right wording i guess i should have said it was running out of fuel after i found that soft and old line
 

johnnyreb

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hi thanks for the replay the motor is setup right i have built many motors over the year and take no shortcut when it come to motor builds

the fitech set up i made the mistake of useing fitech fuel command center which the mechanical pump could not keep up with the fuel command center but the mechanical pump is brand new i put it on when i built the motor.

so after i wrote this post i went out and pulled the tank because i need new one to correct the broken filler neck on the tank and found out the fuel hose coming out of the tank is very soft and coming apart inside so now im think that hose was closing off at a idil and not allowing fuel to come though intill i rev it up demanding more fuel than the line would stay open

btw im looking for a good tank if u know anyone that has one for sale i will pay shipping

and i havent been able to get it to run long enough to do any fine tuning the maybe 200 miles comment was and is probly a high number because i havent been able to get it to run long enough to do any long trips with it trying die or anything than it has sat for three four years do to my job i handle exploves so my job is really demanding at times
Is it a AIR TECK FUEL PUMP? If so. That could be the problem.They are junk. I went through 5 before I wen to Carter and haven,t had any more problems.
 

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