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[Labrauer]

Ok guys I have done a search on the form to find out about electronic fuel pumps but came up with nothing that has helped me so I am asking if any one has used one with it being a source hooked up to your engine fuel pump but used all the time. I have one to put on my 48 Plymouth coupe but don't have the plate to take the mechanical pump off the car. Should I leave the mechanical pump on the car and just run the electronic pump through that pump still hooked up? Would it hurt anything to just bypass the mechanical pump and use plugs to plug up the mechanical pumps hookups and bypass it all together but leave the mechanical one on the engine? Oh by the way this is a 218 engine and the electronic pump is 6 volt. Any response would be great.

[Plymouthy Adams]

I know a few folks run the electric  pump in conjunction with the mechanical one....the electric is connected to a switch and use primary for priming the carb after the vehicle has set a spell cutting back on engine rotations to fuel the carb for a start.  You can also easily make a blank off plate and gasket, remove the pump and keep in trunk as a limp in device should you have an electric pump failure.  Be careful to inspect that the original bolts if used for the blanking plate are not shouldered to prevent a good torque or too long when threaded into the block..am not sure if there would ever be this issue but just a word to caution to inspect..

[Robert Horne]

I made a plate to replace my mechanical pump, from 1/4 inch aluminum, works great.

I installed my electric pump near the fuel tank.

I read the electric is better at pushing fuel, than installing the pump near the front...

[desoto1939]

I would leave the mechanical pump installed onthe block.  The electric pump needs to be install as close as possible to the gas tank.  These pumps are designed to push the fuel and not pull the fule to the carb.  When you have an electric pump and the mechnaical the electric will force the gas throught the mechanicl even if the mechnaical has an issue.

 

Lets say you are running the car down the road and the mechnical is removed and then the electric cuts out on you then you have no backup and the car dies onthe road.  You then have to work on a hot engine and installthe mechnaical pump will all of its connections.

 

This is a real pain when the engine is hot.  Leave the mech installed.  I have both in my 39 Desoto.  Just my 50 cents worth of information but I know others will chime in.

 

Rich HArtung

Desoto1939@aol.com

[Don Coatney]

There is one possible issue when using an electric pump to push fuel through the mechanical pump. Should the diaphragm in the mechanical pump fail it is possible for the electrical pump to push gasoline directly into the crankcase. If undetected this can cause  engine failure and possibly cause the crankcase to explode.

[Phil Martin]

Be sure and check fuel pressure after you install electric pump. Mine had too much pressure and over flooded carb. Used a regulator between pump and carb.

[desoto1939]

don:

 

I think if the diaphram breaks this is only stopping the pump from creating a suction to bring fuel up from the tank.  If I remember correctly there are two screens and holes inthe body that feed fuel into the body of the pump.  But again I am not an expert on this so I might have to look at one of my pumps. 

 

Rich Hartung

desoto1939@aol.com

[Labrauer]

Thanks guys for the response but I have another question to add to this topic. If I install a fuel pressure regulator to the gas line there seems to be a gas return. So where do I hook this line up? Also should I put the regulator between the pump and carb or between the tank and pump? And one more thing what should the pressure on the regulator be set at to not flood carb and still get enough gas to zoom down the road? Thanks for the response.

[Lumpy]

My mechanical pump went out long ago, so I put an electric on it, but I bypassed the mechanical pump, and just left it on the engine. I would have to agree with Don that fuel could leak into the engine through a mechanical pump, I think that is a possibility. I think it's better to bypass it, unless you are using the electric pump just to prime the carbs. I'm not sure about the crank case exploding, but it would cause so many other problems that your brain might explode. !!!

 

I believe you would want the regulator close to the carb(s). My carbs did indeed get too much pressure from the pump until I put a regulator in. Mine is mounted on the inner fender, as close to the carbs I as I could get it.

 

I think/believe/guess that the engine/carb(s) need very little pressure. 2-5psi is my wild guess, although the number 3 seems to pop up in my brain. I could be totally wrong on that. I've never put a pressure gauge on mine, just adjusted until everything worked right.

 

My regulator has no gas return, but normally you would have to run any kind of return line back to the gas tank. ? What kind of regulator are you using? I have a Holley on mine.

 

Good luck! Use lots of filters!

 

ken.

Edited February 28, 2014 by Lumpy

[martybose]

I agree with all of the above.  I blocked off the mechanical pump opening, added an electric pump just in front of the fuel tank, added a Holley fuel regulator under the hood feeding a distribution block with a gauge, and motored down the road.  The distribution block is there because I'm running dual Carter-Weber carbs.

 

Marty

[desoto1939]

I just spoke to tech rep at Airtex about this issue of leaking gas if the diaphram broke.  He state that there is a small hole in the body of the mechanical pump that would be used to let the gas come out of hte body and not run into the oil pan and or block.  He stated that you could run this situation to get you home and then swap in a new mech FP  or just block off the old hole for the Mech and run a strainght electric fuel pump model E8011 which is the 6v version of the Airtex.

 

So yes there is a possibility of gas getting into the oil pan and block.  If just using to prime the carb then no issue. 

 

Rich HArtung

Desoto1939@aol.com

[Plymouthy Adams]

Rich..the point Don is trying to make is that the electric if run continuously in conjunction with the mechanical pump would keep a steady stream of fuel flowing through the weep hole instead of the random bit you get with the cam action of the pump...I have seen a many engine fuel pump with  a hole flood an engine..I have also seen the over effects of a fuel pump that is of too great a pressure and floods a manifold...I have seen the results engine blocks blown from excess fuel in the oil sump...one of the first tip offs of such a problem is a sudden dramatic change is gas mileage...

[desoto1939]

PM:  I agree with both of you about the possibility when running the electric full time through the mechnaical.  Thats why I called the Airtex rep to get some more clarification on the topic. And he even stated that running it full time electric and the mech could cause an issue with gas in the oil pan.  Put if you have an emergency then you should be ok but not to run it for a long time that way.

 

We are all learning as we go along in this hobby.

 

Rich

[Don Coatney]

Glad you called Airtex and got that information. One other issue. Should anyone using an electric fuel pump (no matter if plumbed direct or through the mechanical pump) have a crash (severe enough to fracture the fuel line anywhere on the discharge side of the pump) the pump will continue to pump even though the engine is no longer running. And it could pump the gas directly on top of the hot exhaust system turning the driver (who has passed out after his head went through the windshield) into a crispy critter. I could suggest you install an impact switch that would kill the pump upon impact. But it is better if you call Airtex for more clarification.

[Lumpy]

They make switches that shut the pump off when the oil pressure ceases, as in when the motor stops running. I'm not sure how it bypasses that when you are starting the engine, and there is no oil pressure but they do. And there's a lot of things I'm not sure of.

 

I think those are common and easy to find. Summit probably has them.

 

ken.

[T120]

On the after market oil pressure switches I've seen,they use a simple push button switch to bypass the pressure switch when starting the engine.

[Labrauer]

Well guys thanks for all the information and feedback. I think my best bet from reading all your comments is to bypass the mechanical fuel pump leave in the car or make a plate to cover the hole in the block and get a pressure regulator and hook straight up to carb. I have to agree with all on this situation of getting gas to the carb. I have to get the pressure regulator does any of you guys know of a good one? 

[Lumpy]

^{I think the holley's are easy to find, easy to adjust. Nice small unit.}

 

^ken

[mrwrstory]

 I have to get the pressure regulator does any of you guys know of a good one? 

Summit Racing.  Their "Summit" branded unit is the least expensive at something like $28.00.  It's actually the Holley regulator with a Summit label on the Holley packaging.  I've purchased and used three of these over the last 6-7 years and couldn't be happier.  A good value.  Also comes in black.

http://www.summitracing.com/parts/sum-g3032/overview/

[Oldguy48]

I'll add my 2 cents to this discussion. I installed a "Mr. Gasket" 12V Model 12S electronic fuel pump in my P15. It lasted a little over a year, and then failed completely. Fortunately the failure occurred while the car was in my garage. I replaced it with an Edelbrock unit. Pricier, but much better quality. So far, so good. And I also wired in an "Inertia Switch" to disable the fuel pump in the event of a collision. You can obtain the inertia switches at the local Pick & Pull from Ford Explorers and Rangers for a few dollars each. Cheap insurance, I think.

Wayne

Edited March 3, 2014 by Oldguy48

[Lumpy]

I have not had very good luck  with the "airtex" type pumps, the pulsating ones. I've seen dozens of those pumps, identical, but with dozens of different brand name on them. I now have a rotary pump, I actually forgot the brand, I got it at NAPA. It's a much better pump.

 

ken.

Edited March 4, 2014 by Lumpy

[fstfish66]

I have not had very good luck  with the "airtex" type pumps, the pulsating ones. I've seen dozens of those pumps, identical, but with dozens of different brand name on them. I now have a rotary pump, I actually forgot the brand, I got it at NAPA. It's a much better pump.

 

ken.

would be nice to have this  info on the rotary pump

[fstfish66]

there should be info on the pump some where,,,internet,,box etc of what the  pressure is of the pump,,,most stock non racing type pumps are low pressure not needing a regulator,,,you can  but fittings to  install a small fuel pressure gauge in line its the only way to tell what kid of pressure you have,,,there is a regulator  sold at  pep boys and  other parts stores,,,that has a numbered dial on it for pressure,,,,

 

remember this there is NO  electric  fuel pump thatg will live for ever,,,and most  quit sooner then you would like, heat is there enemy,,,they over heat and quit,,,if  you get a in tank style  electric pump it will live a long time,, the fuel cools the  windings,,,,

 

the best pumnp ive found is the carter electric made by  fedral moguel carter is not in  busniess any longer,,, but  fedral mogal  makes some of there parts still,,, and edelbrock re pops the  carter afb  style carb,,,

 

there  is a 12 volt carter pump out of the box pressure is 4 to 6 psi,,  the 2 i have  only show 4 psi a little low for my   4 bbl engine but  its not a race car,,, not sure if they have a 6 volt version,,

 

mechanical is way more dependable  over elecrtic

[Lumpy]

Thanks for jogging my memory! The pump I have now is the Carter, and it's a 6V.

 

One nice thing about a regulator, once you get it set where you want it, you can change pumps and still get the same pressure.

 

ken

[Labrauer]

You guys are so helpful on what I need to do for the gas delivery problem that I have. I thought that I would just bypass the mechanical pump and go with the electric one but now I am having second thoughts about that even. If they are making new mechanical fuel pumps I am now thinking this is the way to go. Just replace the mechanical one with a new one. What is the difference in single action and the double action pump. Does the double action pump put out more gas and how does it work?