Engine/Transmission (1998.5 - 2002) Electric lift pumps vs mechanical..............

[FTwardoch]

... ... ... ..... seems after being a member here and on NWBombers it is unreal how many issues you read about lift pump problems... ... ... ... ... and not just the stock units. It would seem the 'recommended' fix is a FASS but even they seem to have problems (again, this is a SOP feeling from reading message boards for a long time). So my thinking is for RELIABILITY purposes, why don't more guys use a mechanical fuel pump? Is it cost? Aside from going the expensive route (new cam that allows a P-pump style setup) what else is there? An add-on belt driven Mitusa like I saw in DieselPower magazine on a Duramax? Something like it?



Weigh in please... ... ... ... . just seems like a no-brainer to me on the surface.



Hope y'all had a great Thanksgiving!

 

[wlowe]

I'm not an expert on mechanical fuel pumps, all I know is what I've read. It seems that the mechanical pumps are very reliable and have no problem delivering plenty of fuel. In my opinion the biggest drawbacks are cost and the fact that you need an electric pump to start the engine, so you're still stuck with the reliability issues of electric pumps. That being said, the electric pump would probably last longer since its only use is to start the vehicle.

 

[RHestand]

I would also like info. on a mech. fuel pump. It's been my experience with gas engines, that a good HP mech. pump is much more durable than an elect. pump.

I'm not sure I want to change my cam for a mech. pump, but a good belt drive sounds interesting.

 

[BarryG]

I have a RASP which is the pump that the Mitusa is a take off from. It does not require an electric pump to start the vehicle. My electric pump has not been hooked up for 80k and my truck has started every time. The electric makes a great automatic backup in case the mechanical should throw a belt (which mine hasn't) and it makes an easy way to prime the sytem if you open it up but it is not required to start the truck. It has solved my worry about fuel pumps.

 

[ThrottleJockey]

The RASP does'nt require an electric lift pump to start anymore? When did that change?

 

[FTwardoch]

I have a RASP which is the pump that the Mitusa is a take off from. It does not require an electric pump to start the vehicle. My electric pump has not been hooked up for 80k and my truck has started every time. The electric makes a great automatic backup in case the mechanical should throw a belt (which mine hasn't) and it makes an easy way to prime the sytem if you open it up but it is not required to start the truck. It has solved my worry about fuel pumps.

So does the RASP require the cam change?

 

[darkhorse]

So does the RASP require the cam change?

No. It's belt driven.

 

[rweis]

I decied to go with a Walbro as the backup to my RASP. HOWEVER,



I did some research into using a industrial fractional HP (1/6) to drive a second RASP as the backup. The MTBF for the electric motor is like 5000 hours (150k miles (30 mph average)). Since it only runs 20 seconds when you turn on the key (5000 hrs x 60 min x 3 cycles/min = 900,000 cycles) it should last for quite a while.



I went with a Walbro because of the immediate need to replace the OEM Carter, but will eventually do the industrial motor I think.



The cost of the Walbro was $175 with all the install kit, fittings (AN-6), mounting kit. The cost of the FHDCNV (Fractional HP 12v DC Non Vented) is $120 for the motor, $50 PWM controller to get the correct speed for the RASP, $210 for the RASP, $35 for the direct coupling the motor to the pump $415. ASSUMES you already have the fuel bypass valve back to the tank at the VP44 to bypass fuel and set the VP44 psi (Kinsler JetCan $65 / $480 total).



The other drawback is the FHDC is 11" long, coupling 2", RASP 4" = 17" needed to mount the package. FHDC motor 10# RASP 2# about 12# of backup electro-mechanical LP.



However, parts sourced, and doable.



There is a thread about an AirTex lp that is interesting as well.



More possibilities than there ever have been.



Bob Weis



I do not know if the RASP NEEDS an electric lp. The VP44 has a small cavity of fuel right at the fuel feed port built into the VP44 (ie under the EBC). I do nto know for sure though if that cavity is enough, or if it tends to drain back towards the tank.

 

[RSimmons]

Bob,

This looks like it may be right up your alley with the electric twin gear type pump. check it out.

Fuel Injection Pumps



Anyone ever tried one ?

 

[rweis]

Cool beans!



Have to definitely check that out. Tough motors (I'll get the specs on the motors, but seem to be in about the right amp range for durability and high MTBF) on gear pumps (the absolute best pump chooice - internal gear (gearator), or external gear (the internal longitudinal gear mesh type like the RASP / Fuel Boss / Mitusa). PERFECT combination! I'll check with the local racing crowd to see what they think for reliability and compatiability.



I'll get some pricing to see what the range is and post it.



More options maybe, (think twice, recheck, and test)



Thanks,



Bob Weis

 

[rweis]

The MagnaFuel series is available at Jegs, Summitt, Car Pro Motorsports.



The inline MP 4302 $430

The MP 4301 $470

The MP 4702 $783



I do not know about diesel in them yet. You have to know exactely which pump of the Maganstar series you are looking at as some of them are vane type pumps (which I personally would avoid). If you are going to this much expense you ought to get a gear driven pump ((internal gear pump) gerator or (external gear pump) parallel driven gears)



I think the motor is the key for longevity. Most of the gear pumps are pleanty sufficient to pump the fuel we need. That is why I still think the FHDCNV (1/6 hp) is the long term (define long term in 150k+) way to go, and you choose the components for durability rather than a manufacturer package the pump as a system.



Bob Weis

 

[paulb]

I have a RASP, and have about 110,000 on it. The first 30,000 was without having the stock pump hooked up as a backup, and the RASP worked fine this way. I just decided that the backup would be nice, and having it to prime the fuel system after changing the fuel filter is a good thing. I am still on my orginal belt, though I do have a spare under the seat, and I still am using my orginal lift pump as a back up. I have mine setup to run 18psi pre-filter, which works out to be ~15psi at WOT, at the VP44.



Paul