Mechanical fuel pump

[Rob67bronco]

I have a 1967 bronco with a 170 engine. The fuel pump won’t pick up the fuel from the tanks. Have tried pumps without the vacuum advance tubes on top but still no luck. Tried a ford Fairmont pump but have the same problem. I put an electric pump on and it works fine but would like to be able to stay stock. Any ideas?

 

[bmbm]

Fuel pumps from autozone etc are known to be poor quality nowadays. I read a lot about that lately on fordsix.com. Many on that forum are going to electric pump. Do you have vacuum wipers?

 

[73azbronco]

how sure are you the fuel line is clear?

 

[Oldtimer]

And are the gas caps vented?
My 68 has (had) no vents into the tank, other than the vent in the cap. It is next to impossible to buy vented gas caps in this day and age, despite what the package states.

 

[Rob67bronco]

Fuel pumps from autozone etc are known to be poor quality nowadays. I read a lot about that lately on fordsix.com. Many on that forum are going to electric pump. Do you have vacuum wipers?

No I switched to electric wipers

 

[Rob67bronco]

And are the gas caps vented?
My 68 has (had) no vents into the tank, other than the vent in the cap. It is next to impossible to buy vented gas caps in this day and age, despite what the package states.

Ye

 

[Broncobowsher]

Pull the rubber hose off the suction side of the pump, start the engine. Is it sucking on your finger? Is it blowing on your finger? The pump might be good and have other issues (below) or a lot of people will accidently plumb it backwards.

Another possible issue is a pin hole in the line from the tank to the pump. Could be hard line, rubber, or a joint, or multiple. The mechanical pump at low speed might not be able to suck fast enough to overcome the air leak. Where the electric pump isn't engine speed dependent and might be able to suck hard enough to get you enough fuel. Have you ever tried to drink something through a straw with a tiny pin hole leak in it? Amazing how much air can get through a tiny hole when you are thinking you are going to get something to wet your whistle.

 

[Rob67bronco]

Yes the gas caps are vented. I even took them off and tried to start it that way no luck

 

[Rob67bronco]

Pull the rubber hose off the suction side of the pump, start the engine. Is it sucking on your finger? Is it blowing on your finger? The pump might be good and have other issues (below) or a lot of people will accidently plumb it backwards.

Another possible issue is a pin hole in the line from the tank to the pump. Could be hard line, rubber, or a joint, or multiple. The mechanical pump at low speed might not be able to suck fast enough to overcome the air leak. Where the electric pump isn't engine speed dependent and might be able to suck hard enough to get you enough fuel. Have you ever tried to drink something through a straw with a tiny pin hole leak in it? Amazing how much air can get through a tiny hole when you are thinking you are going to get something to wet your whistle.

 

[Rob67bronco]

All of the hoses from the tanks are nee

 

[Broncobowsher]

All of the hoses from the tanks are nee

New doesn't mean good. It actually makes me even more suspicious.
Hard lines can get pin holes as well. More so if just stressed from putting new hoses on.
Dual tank? That selector valve can create an air leak as well.

 

[stout22]

Are you sure the concentric on the engine is working properly / engaging the fuel pump arm?

 

[ntsqd]

There's at least two classes and two types of fuel hose available these days. Emissions barrier or not, and EFI rated, or not. Then there's quality aspect as a layer over the top of all of that. High quality, EFI Emissions barrier hose locally runs about $5-$6 a foot.
The Emissions Barrier part is the important part, the EFI rating is just a fuel pressure rating increase. Emissions Barrier hose has a liner in it that is impervious to the more aggressive compounds in this stuff they sell under the name of "gasoline." Cheap, non barrier fuel hose isn't worth the trouble. Those aggressive compounds in the fuel eat the rubber and can cause all kinds of mayhem.

 

[Broncobowsher]

There's at least two classes and two types of fuel hose available these days. Emissions barrier or not, and EFI rated, or not. Then there's quality aspect as a layer over the top of all of that. High quality, EFI Emissions barrier hose locally runs about $5-$6 a foot.
The Emissions Barrier part is the important part, the EFI rating is just a fuel pressure rating increase. Emissions Barrier hose has a liner in it that is impervious to the more aggressive compounds in this stuff they sell under the name of "gasoline." Cheap, non barrier fuel hose isn't worth the trouble. Those aggressive compounds in the fuel eat the rubber and can cause all kinds of mayhem.

Yes to all that. The barrier hose is often easier to find as "marine rated fuel hose".
None of that is the same as power steering/automatic transmission cooler hose.
And if doing EFI and need hose for inside the fuel tank, that is yet a different rated hose.

When I was 16, they were all interchangable. Well they would last 6 months to a year anyway. That was a lifetime to me at the time. Now I know better. Correct hose will last decades.

 

[73azbronco]

And are the gas caps vented?
My 68 has (had) no vents into the tank, other than the vent in the cap. It is next to impossible to buy vented gas caps in this day and age, despite what the package states.

1/32 drill bit makes it vented

 

[73azbronco]

There's at least two classes and two types of fuel hose available these days. Emissions barrier or not, and EFI rated, or not. Then there's quality aspect as a layer over the top of all of that. High quality, EFI Emissions barrier hose locally runs about $5-$6 a foot.
The Emissions Barrier part is the important part, the EFI rating is just a fuel pressure rating increase. Emissions Barrier hose has a liner in it that is impervious to the more aggressive compounds in this stuff they sell under the name of "gasoline." Cheap, non barrier fuel hose isn't worth the trouble. Those aggressive compounds in the fuel eat the rubber and can cause all kinds of mayhem.

Nope my brother, auto zone this weekend, per foot, EFI hose is $10,50 per foot.

 

[ntsqd]

And they say CA is expensive!

 

[73azbronco]

Sorry but back in 76, I knew the mechanical pump was a dinosaur. I installed carter 4070, still there. I know it was something like a 4070? Problem is, today those look like like cheap knock offs now, and when you google the carter website, i get the hacker alert telling me it's a stolen website.

 

[ntsqd]

"P4070" is the common version, but there are several to many subtly different versions of that pump. Highly regarded still.
It isn't perfect, but buy things like this from known vendors. Summit would be my choice. Not some random site with the lowest possible price found by a net search or amazon.

 

[Oldtimer]

I have a 1967 bronco with a 170 engine. The fuel pump won’t pick up the fuel from the tanks. Have tried pumps without the vacuum advance tubes on top but still no luck. Tried a ford Fairmont pump but have the same problem. I put an electric pump on and it works fine but would like to be able to stay stock. Any ideas?

Rob,

There may be an issue with the arm on the mechanical fuel pumps?
My experience is with V8, and I have never seen the inside of a I6.
The below thread covers what I found with V8 fuel pumps and eccentrics.

Rollmaster CS3031 timing set and fuel pump eccentric

I am installing a ROLLMASTER CS3031 timing set in my 351W, from a 75 E-250. The original engine had a two piece fuel pump eccentric that is not compatible with the Rollmaster cam gear. The engine is carburated. I need some options. Will a one piece eccentric work? Is there an aftermarket...

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