Attention all fuel systems experts

[fordor41]

Originally Posted by CJStefan

Well shit, that's not good. Have a better pump you can recommend?

I use a universal pump from parts store. $30+ or -. Have worked great for me

[CJStefan]

Ok new question. How much of vapor lock can actually be attributed to the fuel pump? It looks like it's pretty far away from any heat source (head or intake) so I cant imagine it gets super hot. Now the carb on the other hand...I wonder if that's not the majority of the issue. The Chevy 235s use a half inch phenolic spacer between the intake and carb and I dont remember heat ever being an issue. I just ordered one from I think Bob Drake. It was like 30 bucks or so. I also plan on blocking the heat crossovers so that will help a ton I'm sure (I know about cold running issues and all that, dont worry)

[FlatheadTed]

I dont know all there is to know on the subject but these are some thoughts on ti. People blame the alcohol in the fuel but in the day it had alcohol In it H Ford tested the cars in the desert ,over the years GM on here has talked about Coil problems being a source of VP,L . theirs a clue on my web site ,With 6 volt any drop in voltage can contribute ,I recently had this issue were driving for some miles on the motorway got into traffic ,stopped car wouldn't start swapped out cold coil car started ,it took two days to find the problem were Acid had run down the battery cable (fine strands welding cable
) so a voltage drop ,coil function can drop of when they are hot this could mean they are faulty ? . with a Ford /Holly carb its likely to be a power valve leak down, and flooding ,With pumps it can be just sucking air, Ted

[Scotty's 52 F3]

I am running a phenolic spacer and I block my heat risers in the summer. I use a piece of sheet metal with a lip bent on the end so I can slip it in or out from under the intake gasket. Originally I had the factory Holley 94. No vapor lock. Since then I have swapped on a Merc manifold and 2GC carb. Still no vapor lock.

I can drive a load of junk to the dump about 30 minutes away in 100 degree plus temps, shut it off while I'm unloading and it will start and drive home without vapor lock. This is probably why I never got around to the electric pump installation?? Now that I jinxed myself I better buy one for this summer. It can't hurt to have it just in case.

I did have heat related ignition issues when I first got the truck. It would die about a block from the house and only start again after it cooled off. A better coil, condenser and solid core wires fixed it. Fresh cap, rotor and points went in also.

[CJStefan]

I'm going to run pertronix so hopefully I can avoid ignition issues

[CJStefan]

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Originally Posted by Scotty's 52 F3

I am running a phenolic spacer and I block my heat risers in the summer. I use a piece of sheet metal with a lip bent on the end so I can slip it in or out from under the intake gasket. Originally I had the factory Holley 94. No vapor lock. Since then I have swapped on a Merc manifold and 2GC carb. Still no vapor lock.

I can drive a load of junk to the dump about 30 minutes away in 100 degree plus temps, shut it off while I'm unloading and it will start and drive home without vapor lock. This is probably why I never got around to the electric pump installation?? Now that I jinxed myself I better buy one for this summer. It can't hurt to have it just in case.

I did have heat related ignition issues when I first got the truck. It would die about a block from the house and only start again after it cooled off. A better coil, condenser and solid core wires fixed it. Fresh cap, rotor and points went in also.

How thick of sheet metal do you use?

[Scotty's 52 F3]

I don't remember how thick the sheet metal was. It was a couple pieces in my stash of random "stuff" I keep. It was a few years ago. I'm guessing about like a matchbook?

It was just to try it out at the time and it worked out so I never changed it. Pretty sure I slid it between the gasket and block. I greased the intake gasket.

[aussie merc]

all carbs will evaporate gas its just natural heat is your biggest enemy so a resin plate under the carb with an extended shield under the bowl really helps alcohol /corn gas is worst because the boiling point of alcohol is lower also be warned if you run a full time electric pump you should fit a tachometric relay [Key on will run for set time and switch off until it gets a signal from coil this allows it to prime so you can start but in the event of something untoward happening it will shut down the pump if the eng stops

[CJStefan]

Originally Posted by aussie merc

all carbs will evaporate gas its just natural heat is your biggest enemy so a resin plate under the carb with an extended shield under the bowl really helps alcohol /corn gas is worst because the boiling point of alcohol is lower also be warned if you run a full time electric pump you should fit a tachometric relay [Key on will run for set time and switch off until it gets a signal from coil this allows it to prime so you can start but in the event of something untoward happening it will shut down the pump if the eng stops

I was just thinking about that. When I converted my cj7 over to mpi that's how the electric pump works. What exactly makes that happen?

[CJStefan]

I see wiring diagrams on how to hook the tachometric relay up but I'm not finding anything for sale. I'm using a speedway ignition switch that's key start so do I still need one? The pump will run with the ignition in the run position but it should turn off when the keys in the start position, shouldn't it?

[aussie merc]

try the relay unit that they use in LPG installations often called a joker relay[?????] they will run and prime when you turn key on for generally 10/15 seconds then go into a hibernation mode until they get the pulse signal from coil then they will run until that signal stops [engine turned off or stalled ] as for the switch you should have got a contact sheet in the box with the switch unit but as a rule when you go to start the ignition contact will remain live [otherwise it would lose ignition power when cranking and be a bugger to start ]

[CJStefan]

I'm finding some but they're all from Australia. I found one from Peel Electronics on ebay but it's like 40 to ship plus almost 40 for the relay itself.

[CJStefan]

Anybody familiar with edelbrock pumps? The 17303 looks to be about the correct psi but how are they quality wise? I've read a few different threads where the Facet pumps dont last too long as a primary pump. I've read similar with the Carter so I'm looking into other options. Vintage speed has one but it looks like the little Chinese import ones

[Shoebox]

Originally Posted by CJStefan

Anybody familiar with edelbrock pumps? The 17303 looks to be about the correct psi but how are they quality wise? I've read a few different threads where the Facet pumps dont last too long as a primary pump. I've read similar with the Carter so I'm looking into other options. Vintage speed has one but it looks like the little Chinese import ones

Not exactly apples to apples here but FYI, I'm using the Edelbrock 17303 on my John Deere tractor after balking at what JD wanted for a replacement mechanical pump. Works well and it is located real close to the engine (hot).

[aussie merc]

CJ.Stefan try to find a propane installer in your local area they should know what you want [not sure what your local requirements are but here the are mandatory with propane cars ] but $40 dollars freight is about rite freight has gotten frightfully expensive due to covid $50 US dollar part end cost by the time it gets here is often$150AUD

[CJStefan]

I found this https://www.amazon.com/gp/aw/d/B00BN..._1641215459983 which seems to be the same thing. Now I'm just trying to figure out which pump to get. Just when I think I've found one I read about how it doesn't last under continuous use. I have a bosch on my Jeep (mpi) that's lasted but I dont think they make a low pressure version.

[Robz51]

My merc has only had an electric pump for all the 41+years it's been in the family. Never had a vapor lock pro blem. I learned the hard way about mounting locations. The best place I found (because of dual exhaust) is right in front of the left leaf spring mount as the fuel line transitions from the outside to the inside frame (52 merc). I've used several types of pumps from the old pulsating to modern rotary pumps. I currently use the carter pump sold on the Fifth Avenue Garage site. Works great with no regulator. One caveat though, is plug the fuel pump rod hole with one of the several methods out there. I'm going to try a freeze plug in the near future. If you don't pluv it your oil pressure gauge will read low.
Good luck!
Rob

Sent from my SM-G960U using Tapatalk

[CJStefan]

Originally Posted by Robz51

My merc has only had an electric pump for all the 41+years it's been in the family. Never had a vapor lock pro blem. I learned the hard way about mounting locations. The best place I found (because of dual exhaust) is right in front of the left leaf spring mount as the fuel line transitions from the outside to the inside frame (52 merc). I've used several types of pumps from the old pulsating to modern rotary pumps. I currently use the carter pump sold on the Fifth Avenue Garage site. Works great with no regulator. One caveat though, is plug the fuel pump rod hole with one of the several methods out there. I'm going to try a freeze plug in the near future. If you don't pluv it your oil pressure gauge will read low.
Good luck!
Rob

Sent from my SM-G960U using Tapatalk

I was looking at that pump but couldn't swing $90 plus the money for the filter. I just found the same one on Amazon (Carter 180-P90091) for $50ish that comes with the filter so I'll be ordering that. As far as the pushrod hole plug, I read a 7/16" freeze plug fits perfectly in there so that's what I'll be doing. I'm pulling the intake to stick some '49 wheat pennies in the exhaust crossover holes so that'll be the perfect time to do it. What size hose are you using for the pump? The mustang tank outlet I'll be using is 5/16" so I'm hoping I can run that size hose/hardline all the way to the carb. Maybe I'll pass the fuel line over (or through if theres a hole) the frame and run it down the outside to keep it cooler. I also ordered a Bob Drake carb spacer but it turned out to be plastic so I'm sending it back to get a fiber one instead. I'm fighting vapor lock and percolation as much as I possibly can.

[CJStefan]

I'm scratching the freeze plug idea and I plan to use a press fit plug so it can cover the hole in the pushrod bushing. There is something else I'm curious about though...I notice there are block off plates as well as breathers to replace the fuel pump. Is the breather necessary or will the blockoff plate suffice? The cost difference is substantial

[Chuck41]

I have a mechanical pump and had vapor lock issues last summer driving slowly in Yellowstone park in 90 degree weather. I'm convinced it was improper routing of the steel fuel line next to the exhaust pipe where it dives down from the manifold (this engine has dual exhaust). The fuel in the line was boiling -- I could hear it and see the vapor entering the glass bowl on the pump. I replaced the line, routed it per the factory which naturally took it away from the exhaust, used the short rubber line to the pump. No vapor lock issues yet. We'll see how it goes this summer.