Fuel line routing

[Doug&Deb]

I’m currently running an Airtex E-8902 electric pump inline along with a mechanical pump. I use the electric pump for priming and vapor lock. The problem I’m having lately is a fuel starvation issue only on warm days. Turning on the electric pump cures the problem. I’m wondering if the electric pump is creating a restriction that is worsened by warm temperatures. My question is whether I can run a tee and have the electric pump on its own loop? In other words a tee before and after the pump. I’m also considering getting a good Carter pump and eliminating the mechanical pump altogether. Any thoughts?

[DJK]

42 minutes ago, Doug&Deb said:

I’m currently running an Airtex E-8902 electric pump inline along with a mechanical pump. I use the electric pump for priming and vapor lock. The problem I’m having lately is a fuel starvation issue only on warm days. Turning on the electric pump cures the problem. I’m wondering if the electric pump is creating a restriction that is worsened by warm temperatures. My question is whether I can run a tee and have the electric pump on its own loop? In other words a tee before and after the pump. I’m also considering getting a good Carter pump and eliminating the mechanical pump altogether. Any thoughts?

I have no issues with the Carter P5249 and no mechanical pump.(no regulator either).

[Sam Buchanan]

1 hour ago, DJK said:

I have no issues with the Carter P5249 and no mechanical pump.(no regulator either).

 

Same here.

 

If you decide to delete the mechanical pump you might consider modifying the fuel line inside the engine compartment to get it away from the exhaust manifold. Here is how I ran the line across the upper firewall and over to the carb.

 

Edited April 17 by Sam Buchanan

[soth122003]

While I don't have an Airtex fuel pump, I do have a electric fuel pump for prime and vapor lock. I've had it for a couple of years and I have never noticed a fuel issue while running the mechanical fuel pump drawing fuel through the electric prime pump. In another thread I have currently "Air in the Fuel Line", I was troubleshooting a fuel issue. One of my checks was fuel pressure. The prime pump is putting out 3 psi, while the mechanical is putting out 6 psi. Both were steady readings and did not interfere with each other. Turns out is most likely water and old gas combo.

 

Your idea of a t-fitting sounds fine, but you may want to check the condition of the mechanical fuel pump, the state of the fuel (is it good or going bad, water in the fuel, etc..) pinhole in the line that may be affected by the warmer weather, just to name a few. It might also be like you think that the electric pump is creating drag in the fuel. Only way to find out is to check. Not all pumps are created equal. 

 

Sam and DJK also raise good points about doing away with the mechanical pump all together. Me I like original stuff, but with the advent of technology, it might make more sense to upgrade some things to relieve the heart ache of a failure point. (My generator to an alternator after 2 armature failures in 5 years). It all boils down to what you want and then once you decide, all our friends here will chime in with suggestions on how best to do it. 

 

Joe Lee

Edited April 17 by soth122003

[Doug&Deb]

Joe, my mechanical pump is new and didn’t solve the problem. The weird thing is that the problem is temperature sensitive and my engine doesn’t run hot (steady 160 degrees). My tank and lines are new. I’m going to try bypassing the electric pump to see if that makes any difference. I never had this issue before I added the electric pump but it didn’t start doing this immediately after so I’m stumped.

[soth122003]

Did you install a fuel filter before the electric fuel pump? I believe the electrics are more prone to fouling than a mechanical due to the motor being fuel cooled. I can't think of a reason the warmer temp would be an issue though, unless the switch from winter to summer blend fuel has something to do with it.

You might want to take a fuel pressure reading at the carb then run a bypass line around the electric pump, take another reading and see if the pump is causing a problem. That's all I can think of right now. Some others might chime in with something else hopefully.

 

Joe Lee

[soth122003]

Forgot to add that you should take a reading of each pump. The electric with the car not running and then the mechanical running. When you take the reading with it running the mechanical pump pressure might not change as it will only check the pressure of the pump not the volume. If you take a reading behind the mechanical pump, it may read vacuum and that may change when you take the electric pump out of the circuit. This may involve installing the gauge a couple of times in two different areas. 

 

Joe Lee

[Doug&Deb]

Unfortunately I don’t have a gauge for checking fuel pressure yet. I guess that’s the next investment. For now I’m insulating the line from the pump to the carb. If that doesn’t work I’ll bypass the electric pump and try that. I just checked the line and found no leaks so that’s good.

[LazyK]

Possible problem with a bypass around the electric pump. with out a check valve When you power up the electric pump it will take the path of least resistance and flow right back in to the pickup line. 

[Doug&Deb]

Yeah I’m not gonna try that. I like the idea of having a backup pump. I didn’t think the tee idea would work just checking.

[soth122003]

This is the one I have. Since it is also a vacuum gage, I use it to tune my engine as well.

 

https://www.harborfreight.com/automotive/diagnostic-testing-scanning/compression-pressure-testers/fuel-pump-testers/fuel-pump-and-vacuum-tester-62637.html

 

Joe Lee

[Doug&Deb]

Joe I have a vacuum gauge that I use for tuning also. How do I use it to measure fuel pressure? And yes I do have a filter before the electric pump but it also has its own filter. I’m wondering if that is causing the problem. The pump filter isn’t removable which is stupid. My filter is new. I change that every spring.

[soth122003]

If it is just a straight vacuum gage, you can't. but most auto vacuum gages double as a fuel pressure gage for low psi/carburated cars. If your gage has numbers before and after the zero it is likely a vacuum/fuel pressure gage. Go to the HB link I posted and look at the face of the gage. If yours looks like that, it's both. To use it as a fuel pressure gage, just use a t-fitting to hook it into a fuel line and pressurize it with the fuel pump. If yours is just a straight vacuum gage, The HB one is only $16 so not like it will break the bank. 

 

I have a second one I bought by accident, thinking I didn't have one, and for the cost of postage I would send it to you except that it will probably cost more in postage than to get a new one at HB. LOL

 

Joe Lee

[Crisjr14]

Ok so I'm trying to find out if I was to get one of those vacuum tester from Harbor Freight where and how would I hook it up any please? Thank you 

[Dave72dt]

23 minutes ago, Crisjr14 said:

Ok so I'm trying to find out if I was to get one of those vacuum tester from Harbor Freight where and how would I hook it up any please? Thank you 

Harbor Feight.com  use their search button for "vacuum gauge"

 

Time to be proactive.  Almost every store, especially nation wide has an internet connection for sales.  I'm not going to look one up for you and post pics or

 links.

[Crisjr14]

I am only asking about if I could get some help as to where to hook up the gauge as I have a dual carb set up as for Internet connection for sales I don't follow you and I am not trying to have you look up anything for me just maybe some PICTURES as to where and how it works sorry I am a newbie to these flat heads just trying to get some help 

[Dave72dt]

My apologies.  I misread hook it up as look it up.  Find a vacuum fitting on the intake manifold.  The vacuum line for the distributor advance may work.  An air flow meter to balance the carbs might do you more good.

[soth122003]

Chrisjr14, Since you have a 53 dodge, I going to guess you have electric wipers. Since you have dual carbs what kind of carbs do have? If you have the B&B, at the carbs at the base should be a plug for the vacuum advance. Pull the plug and install a barb nipple fitting and hook up the vacuum gage there. You only need to use one of the carbs, not both. I believe all down draft carbs have this plug, but I won't put money on it.  Also since you have dual carbs, I'm guessing you have a split manifold? If the manifold is an original modded to a split, check at the number 6 intake and see if there is a plug there. If so pull the plug and install a barb nipple there instead. That was for the vacuum wipers on other cars.

 

Joe Lee

Edited October 13 by soth122003

[Crisjr14]

No worries Dave and soth I do have electric wipers and my carbs are the carter b&b so with using only one carb to check the vacuum it will be good enough for both carbs then? And yes they do have the plugs thanks a lot guys I appreciate it 

[soth122003]

Should be. The vacuum is produced by the engines piston on the intake stroke. My hook up is at the no. 6 area on the manifold, so how it would measure the no. 1 piston area is a mystery. lol. Any who, if you want to make sure, you could put nipples in both carbs and connect them with a t fitting, but I don't think it will make a difference. You can search the threads for vacuum gage results and learn what the different readings mean. It might also have it in your service manual.

 

Joe Lee