Mechanical Fuel Pump ?

[albersj51]

I put in an electric fuel pump, but left the mechanical pump in place (just in case). Is there some negative I am not considering by leaving the pump in, but not hooked up to anything? My assumption is that its just moving air from one side of the engine bay to the other. If I am risking damage, please let me know! I'd rather not set up a blanking plate, since I want it there if my e-pump fails, so if I need to "plug" the inlet and outlet, I'm open to ideas.

Thanks!

J

[TJR]

don't plug, simply Connect the outlet to the inlet.. and let the air recirculate back and forth

more here... http://www.roversnorth.com/forums/showthread.php?t=7496

[albersj51]

Thanks, TJR! I read that post, but I thought I remember someone saying it could damage something...but I guess not since I can't find that statement again. Recirculate it is!

[I Leak Oil]

Why put all that wear on the pump if you don't have to? Make a simple blanking plate to block off the opening and keep the pump in the truck as a spare. You'll know it will work if you need it.

[Terrys]

Personally, If the mechanical pump was working good enough to warrant leaving there, it was good enough that I didn't need the electric one. Certainly the mechanical pumps are more reliable than the electrical system.

[luckyjoe]

I agree with Terrys post. It sounds to me like you might be better served by carrying a spare mechanical pump.

[LaneRover]

If it is too keep it as an attached spare, then wouldn't it wear it out pumping away all the time, even if it is pumping nothing?

[TJR]

If it is too keep it as an attached spare, then wouldn't it wear it out pumping away all the time, even if it is pumping nothing?

Sure the pump would be in "use", if the in/oulets are sealed off(conected) theres no real risk of damage other than the pump normal wear and tear.

If it were me, I'd carry a universal electric pump, some wire and zip ties. and keep the mechanical one in use. In my old days of 4x4'n, I did just that and the universal 12 v electric pump was used a few times on others rigs. Once even feeding from a gas can. luckily I never needed it myself.

..Talbot

[amcordo]

Out of curiosity, where did you install the electric fuel pump?

[Sputnicker]

The biggest negative for leaving the existing pump in series with an electric pump is the potential for a diaphragm leak, which would allow raw gas to get pumped into the crankcase by the electric pump. The main benefit is redundancy/reliability - if either pump fails, the other will get you home.

There were some recent threads on mechanical pumps and a lot of folks (including me) have had bad experiences with aftermarket mechanical pumps. They look exactly like the original AC, but seem to have a high failure rate.

For now, I have both in series, but I will likely eliminate the mechanical pump and install a blanking plate. And carry a spare electric.

Based on a web-search and recommendation by Teri Ann, I went with the Facet Posi-Flo (the lower pressure version), which is available at NAPA stores for about $50. I mounted mine on the main frame rail under the right-hand floor panel.

[TeriAnn]

Based on a web-search and recommendation by Teri Ann, I went with the Facet Posi-Flo (the lower pressure version), which is available at NAPA stores for about $50. I mounted mine on the main frame rail under the right-hand floor panel.

It is an inexpensive, reliable pump but it is also righteously noisy. I hope you soft mounted it to insulate it from the frame. Personally I would go with the mechanical fuel pump every time I can.

[Wander]

The e-pump on my IIa is mounted on the underside of the seat box right under the middle seat which is works for me as the PO also moved the tool bin cover to the middle so I can open that and get right to the pump.

He cut a square out of the front of the seat box to access the bin which is right below the D/S- interesting mod that goes along with the extra storage box he added between the gas tank support and the front outrigger with a cover on the P/S floor. It's kind of a secret bin with the floor mat covering it- I guess he was running shine out of the hills or something:cool:

[albersj51]

I mounted mine next to the gas tank, but slighly lower. Read on here they push well, but pull poorly, so having it lower works well.

I am not running it through the mechanical pump because of the leak risk; I bypassed the mechanical pump entirely.

I know many prefer the mechanical pump, but this was a very hot summer in SC and I ran into some vapor lock issues, so I took Gudjeons advice and ran a bypass filter before the carb (also have a filter before the e-pump) so any excess pressure/vapor can be returned to the tank. He and a couple old school mechanics recommended an e-pump to prevent vapor lock.

[Sputnicker]

My plan after the rebuild was to use a mechanical pump. My original AC had served me well for 35 years. I liked that it was so simple and I planned to carry a rebuild kit, just in case. My AC was pretty well worn, however, so I bought the carbon copy after-market version (with no manufacturer's name on it). It ran great for the first 100+miles and then quit unexpectedly. I disconnected the pickup hose and put it in a jar of gas with the outlet running into a second jar. No amount of hand priming or battery cranking would produce any flow. That ruled out vapor lock as the cause. It wouldn't even pump when I tried it on the bench using the lever that rides on the cam. I verified that both valves were opening and closing as intended by applying suction and pressure. I took it apart and found nothing obviously wrong. My guess is that the shaft on the diaphragm was sticking and/or the spring on the diaphragm was too weak to overcome normal friction. While waiting for a replacement, I reassembled and reinstalled it and it ran for a while and quit again. When I got the replacement (same after-market pump), I installed it and that one failed too. It started with a misfire under load and then quit altogether.

So that experience and similar complaints by others on the forum are what drove me to opt for the electric pump.

I did use rubber mounts and it is a bit noisy, but only until all the other Land Rover noises drown it out. I also have a filter before the pump to keep it free of debris.

[TJR]

My plan after the rebuild was to use a mechanical pump. My original AC had served me well for 35 years. I liked that it was so simple and I planned to carry a rebuild kit, just in case. My AC was pretty well worn, however, so I bought the carbon copy after-market version (with no manufacturer's name on it). It ran great for the first 100+miles and then quit unexpectedly. I disconnected the pickup hose and put it in a jar of gas with the outlet running into a second jar. No amount of hand priming or battery cranking would produce any flow. That ruled out vapor lock as the cause. It wouldn't even pump when I tried it on the bench using the lever that rides on the cam. I verified that both valves were opening and closing as intended by applying suction and pressure. I took it apart and found nothing obviously wrong. My guess is that the shaft on the diaphragm was sticking and/or the spring on the diaphragm was too weak to overcome normal friction. While waiting for a replacement, I reassembled and reinstalled it and it ran for a while and quit again. When I got the replacement (same after-market pump), I installed it and that one failed too. It started with a misfire under load and then quit altogether.

So that experience and similar complaints by others on the forum are what drove me to opt for the electric pump.

I did use rubber mounts and it is a bit noisy, but only until all the other Land Rover noises drown it out. I also have a filter before the pump to keep it free of debris.

As others indicated the orig AC pump has always worked for me.. (when the LR was on the road) I bought a proline replacment for better or worse.... I guess now I'm, crossing my fingers.

[greenmeanie]

One aspect of the mechanical pump not mentioned yet is that it can fail slowly with an imperceptible effect that only shows on the high end. I ran the original mechanical pump for years and chased performance on my truck as I was using it on the freeway as my DD. I went through the usual carb swaps, 8:1 head, cam swap etc. but in the end it was only when I was perduaded to swap to a 'lecky pump by Yorker matched with a Rochester carb that I found that I could run at 65mph on 32' rubber witout an overdrive and 75mph with. The old pump was putting fuel through but not enough to feed the old lump at full chat. THis gradually got worse until she finally stopped completely on the trail one day resulting in a tow out froma friends Jeep.

For those with performace that won't exceed 55mph this is something to check.