Inline electric pump and mechanical pump questions

[96Formula6sp]

Hey guys our lemons car is having a weird fuel delivery problem. Current setup is a stock 1986 318 with a 600 cfm Eldelbrock carb. The fuel system has a the stock 5/16 line coming from the tank to the a new mechanical pump on the engine block. The outlet of the pump has a fuel filter on it as well as a homemade fuel cooler(I will get to the cooler in a minute). We are having issues with the small clear fuel filter staying full. Almost feels like vapor lock. Being this is a 24 hours of lemons car we do not need these issues. Below is a list of things we have checked.

- Fuel tank was dropped and is super clean inside with no rust.
- Fuel pickup from the tank is clean. Sock looks in very good shape.
- Checked the factory hard line. No kinks or damage. We have blown it out and nothing came out. Air flow is strong both directions.
- Put a pump on the 5/16 line and with surge pump it was flowing at a good rate. Got two gallons in about three mins.
- New fuel filter has gone on but the old ones look fine.

So our first race we had a fuel issue like this which turned out to be a failed fuel pump. It was worn out. We replaced with a new fuel pump and our fuel filter seemed to stay full. Our second race was much cooler but still no issues with the fuel filter staying full. Our test day came and we were having issues with the fuel filter staying full. Filter looked good but we changed it anyways. We also put a new mechanical pump on the car. No changes. We then added a fuel line cooler. This is on the outlet side of the pump and we have a 4ft section of 5/16 hard line on the grill. On the last test day this was keeping the fuel filter full again.

Fast forward a few weeks later we are starting to have issues with the fuel filter staying full at all at this point. So now we are debating throwing a electric in line pump to help the mechanical pump. Is this ok to do or should we just delete the mechanical pump. Tired of fuel delivery problems or what looks like to me is vapor lock. Figure an electric pump could help the mechanical pump out and keep out small fuel filter full. Just tired of this and what buddies have said is get an electric pump.

 

[PurpleBeeper]

I don't know if this will help, but my see-through fuel filter up near the engine has always been about 2/3 full.

 

[khryslerkid]

If it's starving for gas it could be a loose eccentric on the cam gear that operates the pump leaver.

You can run an electric pump with your mechanical installed. Gas passes straight through it wether is working or not.

You didn't state that it's starving for gas. Running out of power and trying to stall.

 

[67 GTX]

Wa the car actually cutting out at certain points? Certain filters, depending how the orientation is mounted, the filter doesn't always fill up when in use.

 

[96Formula6sp]

I don't know if this will help, but my see-through fuel filter up near the engine has always been about 2/3 full.

I have been happy with 2/3 full in the past. Right now we are lucky for it to have any liquid gas in it all all. You can tell it has some pressure in it. So probably vapor locking.

If it's starving for gas it could be a loose eccentric on the cam gear that operates the pump leaver.

You can run an electric pump with your mechanical installed. Gas passes straight through it wether is working or not.

You didn't state that it's starving for gas. Running out of power and trying to stall.

The eccentric is new. Our current used engine had one of the plastic timing gear sets. We swapped the timing gear from a blown engine that was new as well as the new eccentric. Tho the old one looked fine.

Its not starving for gas yet. Can lot drive and idle all day. However its going road racing and the last time this happened at CMP we got about 5 laps then it would begin to fuel starve. Just asking for more fuel lap after lap. Just remember having to go two easier laps then I would have gas for a lap or so. Trying to solve this problem for good.

Was the car actually cutting out at certain points? Certain filters, depending how the orientation is mounted, the filter doesn't always fill up when in use.

Car has not cut out yet. But when your going a lot of wide open throttle it can run out. Filter is mounted 90 degrees at the moment. But at some points it goes empty due to vapor lock. You can sometimes watch it pulse some fluid in once things have cooled off. I would take a filter at half full with some liquid in it. But most of the time its just a gas which is just vapor lock.

 

[EARLY B]

I have been happy with 2/3 full in the past. Right now we are lucky for it to have any liquid gas in it all all. You can tell it has some pressure in it. So probably vapor locking.



The eccentric is new. Our current used engine had one of the plastic timing gear sets. We swapped the timing gear from a blown engine that was new as well as the new eccentric. Tho the old one looked fine.

Its not starving for gas yet. Can lot drive and idle all day. However its going road racing and the last time this happened at CMP we got about 5 laps then it would begin to fuel starve. Just asking for more fuel lap after lap. Just remember having to go two easier laps then I would have gas for a lap or so. Trying to solve this problem for good.



Car has not cut out yet. But when your going a lot of wide open throttle it can run out. Filter is mounted 90 degrees at the moment. But at some points it goes empty due to vapor lock. You can sometimes watch it pulse some fluid in once things have cooled off. I would take a filter at half full with some liquid in it. But most of the time its just a gas which is just vapor lock.

Try running with gas cap loose, the cap may not be venting.

 

[96Formula6sp]

Try running with gas cap loose, the cap may not be venting.

Well its the locking style. So loose would mean it would be in the non locked position and would fall out. Our tank vent is setup with just the hose off the tank up to the top of the car. Charcoal canister is out of the car. Not sure if that affects anything.

 

[tonysrt]

Have you thought of running 3/8 fuel line? I just put one on my 74 Duster to eliminate any kind of fuel starvation problems. Also put in a tanks inc. tank and electric pump.

 

[96Formula6sp]

So last night we ordered a cheap summit racing external pump. Reviews were decent. Plan is to run both for now. We might go ahead and cut the junk fuel pump I have laying around to use as a homemade delete plate. Also got a fuel pressure gauge to add into the system. This way we can watch it. We have had a pain in the butt time with the car in the last little bit. So will figure something else out long term if we keep the car. There is some talk of selling it.

If we make it threw this race and keep the car we will figure our a long term solution if this problem if these do not fix the current issues.

 

[96Formula6sp]

So giving an update to the thread. We ordered the electric pump. During the part when looking to install one other guy noticed a kink in the fuel line. So we cut the hard line out and replaced it with some rubber hose. Good news is that on the fuel pressure gauge we installed at the same time we got a constant 5.5psi cold 4.5psi hot. Gauge says a 1psi drop is normal when hot.

Picture of the kink. Behind the place were we tired to cut it off at the 90 degree bend on the bottom of the picture. Amazed we did not see this sooner.

One full fuel filter for 14 hours of racing. No hot start problems no fuel starve problems. Problem seems to be fixed. Ignore the missing alternator belt. We lost that with 45 mins to go.

 

[bearman]

just a thought go down to the parts store and get a 8 pd one way check valve install it on the input side of the fuel pump. this will always keep it full. from the fuel pump up to the carb so it should help with bleed back and stumble. or the second thought is to pull the line from the pump to carb put a half of a hoop in the fuel line so it can't bleed back shape the hoop like your sink pluming that way always fuel at carb. but the check valve would be much better. i see am later to the party but again just a thought.