I have Vapor Lock

348tripower · July 12, 2010, 09:07:41 AM

Help me out with this one. 1951 Studebaker. 454 engine. Mechanical fuel pump on engine. Limited air flow around pump. Limited air flow period!
My plan is to put a Carter electric pump back at the tank with a big fuel filter after it. I seem to be build too much heat in the engine compartment. I am hoping the rear mounted pump will cure the problem. I am hard fuel line to the frame rail and rubber into the mechanical pump inlet and rubber out to the carb.
When this thing starts the vapor lock problem, the engine temp climbs. Probably due to being in a lean condition.
Any other suggestions?
Thanks,
Don

rumrumm · July 12, 2010, 09:40:26 AM

Do you have a phenolic resin spacer between the carb and the intake manifold?

wayne petty · July 12, 2010, 11:28:23 AM

does the car still have winter fuel in it??? lower reid vapor point fuel..

do you have a decent fuel filter before the pump... usually right before the pump???

do you have any super magnets in the tank to pull any oxide sediments to them.. keep them out of the fuel lines... pump and carb??? that reddish powder found in the bottom of most carbs is oxide... it can come from fuel lines rusting also...

do you have a low pressure fuel pump pressure gauge??? can you see if the fuel pump actually holds pressure...

there are two check valves in each pump.. one inlet .. one outlet.. these can get sediment in the check valve.. when this happens.. there will not be enough suction to properly deliver the fuel..

i normally recommend that a cranking full flow test into a 2 liter bottle.. see if the pump volume stays the same with each pulse... nice full pulses... 15 seconds of cranking will do it... should put more than a pint of fuel in that 15 seconds... unhook the primary wires to the coil.. so it won't spark at all.. have somebody else crank the motor while you observe the pulses into the clear bottle...

this also.. when you have a new fuel filter installed right at the pump inlet.. allows the clean filtered fuel to flow at full speed through the pump cleaning some debris out of the check valves.

i had one chevy truck. that would start and die on cold starts.. need to crank for 30 seconds to restart.. i hooked a clear piece of vinyl hose to the hood and to the fuel line at the carb.. i cranked the engine to fill the line.. when i stopped.. the fuel flowed backwards.. all the way to the tank... there was no return line on this pump...

if you have a vacuum gauge.. hook it to the suction side of the pump.. see if it pulls a strong vacuum when you crank the motor.. and holds it.... if not.. and the full flow test does not cure the problem.. replace it..

restricted fuel on the suction side will create low pressure and vapor at lower temp levels..

i have found restricted fuel strainers in the tank...

clogged inline fuel filters...

clogged fuel lines...

crushed fuel lines... crushed by road debris, jack stands.. floor jacks..

one car.. that would not run over 25 mph... was so clogged.. that when i tested the suction side from the front of the car with my hand vaccum pump.. i could pull 25 inches of vacuum and it would take 30 seconds for it to drop to 0... on the line from the tank...

i used a new speedo cable core like a plumbing snake with a power drill... my friend holding the drill and keeping any slack .. while i pushed it in.. the turning motion threaded it into the fuel line to clean it out.. with blasts of carb cleaner from the other end once it was most of the way through..

A huge tip for changing chevy fuel pumps....

set the motor to TDC compression for the number one cylinder.. pull the #1 spark plug.. or the cap to look at the rotor... which ever is easier..

glue the gasket to the face of the fuel pump.. just before you install it.. so it stays put...

pull the engine oil dip stick... stick it through the pump opening in the side of the block.. straight down... get the tip of the dip stick between the end of the push rod and the block... now.. stick the pump lever into the opening.. this pushes the dipstick back.. lifting the push rod out of the way so the pump lever can drop down in front of the push rod.. then the dip stick can come out..

what's neat.. this takes a HUGE PIA job. and makes it simple... you don't have to worry about the hold back bolt.. you don't have to take the smog pump off on small blocks.. just be sure to disconnect the battery... as on most cars.. you are going to stick the dip stick down behind the alternator... to get it in the block opening..

why worry about where the crank is set... with the cam set to fire the number one .. the eccentric lobe for the fuel pump is at minimum..
so the push rod can be fully retracted...

wayne petty · July 12, 2010, 11:49:11 AM

something everybody should download..

the 14 page Fram performance filters catalog..

the HP1 fuel filter is on page 9..

http://www.fram.com/pdf/Fram_HP_Product_Specs.pdf

one might also want to check into ACDELCO Part # GF62 fuel filter assemblies...

as they are full flow.. have 3/8 NPTF ports.. will take most fuel pressures up to about 75PSI... probably more.. i don't know the exact rating.. and the best part...

every parts store in the country has replacement filter elements for them.

they can be found under a car fuel injected cad sevilles and eldorados from 76 to 79. but i have seen them under some eldos and sevilles trough 85... with a nice bracket bolted to the top.. and set up with 3/8 inverted flair adaptors screwed in.. look in front of the rear axle

Mikej · July 12, 2010, 03:44:25 PM

Runs good when cold? Try the spacer. It will help if the gas is boiling in the carb. Move fuel lines away from the exhaust. You will need to lower the under hood temps. Header wrap. Take off the hood

The biggest problem is how bad the gas is any more.

348tripower · July 12, 2010, 04:02:04 PM

Quote from: "Mikej"Runs good when cold? Try the spacer. It will help if the gas is boiling in the carb. Move fuel lines away from the exhaust. You will need to lower the under hood temps. Header wrap. Take off the hood The biggest problem is how bad the gas is any more.

I have the insulating gasket under the carb. Wraped the exhaust pipes. I just ordered a new Carter pump and Fram filter. Seems that it happens at speed just as well as when going slow. Checking the small clear filter I have near the tank shows rust particles floating. I have a feeling there is some restriction there also adding to the vapor lock problem.
Don

wayne petty · July 12, 2010, 04:44:13 PM

the small glass filters with the white nylon replaceable filters DO NOT CATCH rust or almost anything...

they will let it all through... use them to see the fuel in the lines only... with an element ..

use inline filters for fuel injection.. similar to this one..
it goes on with hose clamps... is steel bodied... and has a big element inside that will filter tiny tiny particles...

Az Filters/Fuel Filter
For your 1985 Ford Tempo 2.3L TBI HP 4cyl
Part Number:   FF679
Weight:   0.49 lbs
Manufacturer:    Champion Laboratories, Inc.
Outside Diameter:    3.11 in. (79 mm.)
Inlet:    0.31 in. (8 mm.)
Outlet:    0.31 in. (8 mm.)
Height:    5.70 in. (145 mm

i used to use the delco GF 61 5/16 inline fuel filters.. the old ones worked so good.. you could get clean gas out of the carb side.. and rusty water out of the tank side... the current batch is not quite as good..

i put them on all kinds of cars... including one .. with a volvo 122S.. all went well.. until he took it off to shake the rust out.. and he put it on backward... so the pump and both carbs filled with chunks of stuff from the tank..

enjenjo · July 12, 2010, 05:16:51 PM

I have been using a Facet electric pump in the rear. The advantage to them, you can draw fuel through them no problem, so you can turn it on only when you need it.

The best way I have found to cure this problem is a return line, so the hot fuel is bypassed back to the tank. But both a return line and an auxiliary pump would not be overkill.

38HAULR · July 12, 2010, 05:39:06 PM

I cured a vapor prob with the simple fitment of a rear mounted Facet pump ,ditching the mechanical pump.
This thread also reminds me of a SBC 283 supplied by a Jag electric pump ,this used to starve under heavy acceleration,the pump did not like the porous bronze filter fitted to the stock Chev 2brl fuel inlet.fitting.
Frank.

348tripower · July 13, 2010, 05:55:13 AM

Quote from: "enjenjo"I have been using a Facet electric pump in the rear. The advantage to them, you can draw fuel through them no problem, so you can turn it on only when you need it.

The best way I have found to cure this problem is a return line, so the hot fuel is bypassed back to the tank. But both a return line and an auxiliary pump would not be overkill.

Do you have a recomendation for attaching the return line to the carb?

enjenjo · July 13, 2010, 11:59:19 AM

A couple ways.

Holley and others make a bypass fuel regulator that you can plumb a return line to, and have the bonus of adjustable fuel pressure to the carb.

Weatherhead has a fitting, 63x5 , that has a built in check valve. The valve can be reversed to work in the direction you need, and is adjustable reliably from about 4 psi to 10 psi. You can Tee this into the line from the fuel pump to the carb, and when the float closes, it will bypass fuel back to the tank.

You can also solder one leg of a Tee shut, and drill a hole about .060" in the solder, plumb this into the fuel line between the carb and pump, and attach the return line to the leg with the solder in it. This method is not as good as the first two, because it's a compomise on size, but it will work, and actually works pretty good when using a GM TBI pump with a carb.

348tripower · July 13, 2010, 03:45:25 PM

Thanks.

Quote from: "enjenjo"A couple ways.

Holley and others make a bypass fuel regulator that you can plumb a return line to, and have the bonus of adjustable fuel pressure to the carb.

Weatherhead has a fitting, 63x5 , that has a built in check valve. The valve can be reversed to work in the direction you need, and is adjustable reliably from about 4 psi to 10 psi. You can Tee this into the line from the fuel pump to the carb, and when the float closes, it will bypass fuel back to the tank.

You can also solder one leg of a Tee shut, and drill a hole about .060" in the solder, plumb this into the fuel line between the carb and pump, and attach the return line to the leg with the solder in it. This method is not as good as the first two, because it's a compomise on size, but it will work, and actually works pretty good when using a GM TBI pump with a carb.

river1 · July 13, 2010, 07:10:54 PM

Quote from: "348tripower"
Quote from: "enjenjo"I have been using a Facet electric pump in the rear. The advantage to them, you can draw fuel through them no problem, so you can turn it on only when you need it.

The best way I have found to cure this problem is a return line, so the hot fuel is bypassed back to the tank. But both a return line and an auxiliary pump would not be overkill.

Do you have a recomendation for attaching the return line to the carb?

i know that for the Caddy 500 they have a fuel pump with a return port on it. is a similar pump available for the chevy 454?

later jim

enjenjo · July 13, 2010, 07:42:24 PM

Quote from: "river1"
Quote from: "348tripower"
Quote from: "enjenjo"I have been using a Facet electric pump in the rear. The advantage to them, you can draw fuel through them no problem, so you can turn it on only when you need it.

The best way I have found to cure this problem is a return line, so the hot fuel is bypassed back to the tank. But both a return line and an auxiliary pump would not be overkill.

Do you have a recomendation for attaching the return line to the carb?

i know that for the Caddy 500 they have a fuel pump with a return port on it. is a similar pump available for the chevy 454?

later jim

Yes, they are available for most engines. Used mostly in the 70s. But if you have a high volume pump, or an electric pump, and want to keep it, the above methods will work.

kb426 · July 13, 2010, 09:07:14 PM

My Dodge crewcab that I pulled the racecar with gave me a few problems. I ended up running a Carter electric pump next to the tank. I bypassed the stock pump because I didn't want the heat from the engine. I ran a line on the outside of the frame to the front of the truck. I put a fram clear filter in front of the radiator support behind the bumper trying to have the gas at ambient air temp. Then I ran a rubber line to the carb. This truck ran 400 miles before stopping for anything. This worked for me the best of all the things I tried. 440 Dodges have alot of iron. At 200 miles, just about everything on the truck was the same temp. Engine, radiator, floor boards, bumper, you name it. it didn't have motor home heads and would cook the valve cover gaskets in about 10,000 miles. It also melted the master cylinder. Sound like fun yet?