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Topic: Add electric prime pump to 8.3 mechanical engine? (Read 664 times) previous topic - next topic

Add electric prime pump to 8.3 mechanical engine?

I'm going to preemptively change my fuel lines and am pondering the possibility of adding an electric prime pump, either inline or parallel with a couple stop valves to the fuel supply line. 
The mechanical pump on the engine seems pretty much worthless for anything other than building hand strength. 

Does anyone know if this would be possible/advisable?  Would it be able to purge air back down the return line after injector pump? 

Chuck
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS

Re: Add electric prime pump to 8.3 mechanical engine?

Reply #1 –
Chuck, As you know, I'm new to these big diesels, cummins and Foretravel setups in particular.

However, I found that what worked for me (on my boat), was to push fuel from the tanks with a simple AC Delco automotive pump available at Napa or anywhere for very little $ and then Pull fuel towards Racor filters and engine, with a better pump.  Choice of pump is a Walbro.  both are wired to a simple toggle switch so I can run these pumps for a few seconds or so, before trying to actually start the engine.  This bleeds any possible air from anywhere in the system. Always a quick start!

 I also use the "stop" solenoid to cut fuel supply so to lubricate the internals of the engine prior to putting compression loading on dry bearings etc..... I can turn the engine over for a few seconds, until I see nice oil pressure building/prelubricating the bearings, etc.  Then I 'release the Stop Button' and fire it up.

Not sure how this can work on FT's but sure someone will have good suggestions if it's an idea worth contemplating.

Coach Build # 5862/40'/2001/U320/Motorcader 17136

Re: Add electric prime pump to 8.3 mechanical engine?

Reply #2 –
I should add, that I removed the mechanical fuel pump from my boats engine and have relied totally on the electical systems aboard.
Coach Build # 5862/40'/2001/U320/Motorcader 17136

Re: Add electric prime pump to 8.3 mechanical engine?

Reply #3 –
Quote from: Chuck Pearson –
I'm going to preemptively change my fuel lines and am pondering the possibility of adding an electric prime pump, either inline or parallel with a couple stop valves to the fuel supply line. 
The mechanical pump on the engine seems pretty much worthless for anything other than building hand strength. 

Does anyone know if this would be possible/advisable?  Would it be able to purge air back down the return line after injector pump? 

Chuck

Chuck,

A guy named Tom Hall did exactly that down the road from me in Sacramento. Think I would leave the main mechanical supply pump installed as the engineers may have figured in the amount of fuel the engine would need at full throttle plus extra to carry off heat from the injectors back to the fuel tank. Perhaps also other little things that diesel engineers consider.

Before I go any further, here is the web site with the illustrations and part numbers, etc. The gold check valve was cracked in my coach so I replaced it. Ordered from a local trucking company for about $37. Anyway: Tom Hall

For owners that modify the engines to get more HP, the fuel lines may have to be changed out to a larger I.D. As you move more fuel, the friction loss goes up and with a coach with the fuel tank up front, it's a long ways back to the engine.. I know on Porsche 930s with 2 turbos, both the supply and return line have to be changed and that's only 6 feet or so. Bad deal to go lean on a gasoline car when putting out a lot of HP.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Add electric prime pump to 8.3 mechanical engine?

Reply #4 –
Quote from: MemoryRoads –

However, I found that what worked for me (on my boat), was to push fuel from the tanks with a simple AC Delco automotive pump available at Napa or anywhere for very little $ and then Pull fuel towards Racor filters and engine, with a better pump.  Choice of pump is a Walbro.  both are wired to a simple toggle switch so I can run these pumps for a few seconds or so, before trying to actually start the engine.  This bleeds any possible air from anywhere in the system. Always a quick start!


Ron, leave it to an old blowboater to figure this out.  I had my boat lose power...completely, not once but twice inside the Port Aransas Jetties due to fuel delivery problems.  Rocks on either side, tankers sliding by yikes.  Sounds like what I'm thinking about except I'll most likely leave my mechanical pump in place as Pierce suggests.

Quote from: Pierce & Gaylie Stewart –
Chuck,

A guy named Tom Hall did exactly that down the road from me in Sacramento. Think I would leave the main mechanical supply pump installed as the engineers may have figured in the amount of fuel the engine would need at full throttle plus extra to carry off heat from the injectors back to the fuel tank. Perhaps also other little things that diesel engineers consider.

Before I go any further, here is the web site with the illustrations and part numbers, etc. The gold check valve was cracked in my coach so I replaced it. Ordered from a local trucking company for about $37. Anyway: Tom Hall

For owners that modify the engines to get more HP, the fuel lines may have to be changed out to a larger I.D. As you move more fuel, the friction loss goes up and with a coach with the fuel tank up front, it's a long ways back to the engine.. I know on Porsche 930s with 2 turbos, both the supply and return line have to be changed and that's only 6 feet or so. Bad deal to go lean on a gasoline car when putting out a lot of HP.

Pierce

Thanks for the link, the gold check valve sounds like a nice option as I was thinking about putting in a loop that would require bypass valves.  Don't think a small elec pump would pass enough flow.  However, I, unlike you, am "blessed" with an injector pump and banjo fitting pressure regulator.  I'm behind the curve on fuel routing on this engine and don't know how far the pump would prime the Cummins, if it would push fuel through the whole circuit into return lines it would be perfect. 

While we're on the subject, I'd like to publicly retract some disparaging comments I made in the past regarding 2 stroke Detroits.  I recently spent some time aboard a boat with a sweet pair of 671T's.  Talking with the capt about what service he'd gotten out of em, how quick and cheap they were to rebuild inframe, and some pretty amazing fuel economy for 20 year old engines got my attention but the thing that really grabbed me was how absolutely sweet they sounded on the pins.  I was outta line in badmouthing a man's engine and I stand corrected. 

Chuck
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS
 

Re: Add electric prime pump to 8.3 mechanical engine?

Reply #5 –
Chuck,

Apologies accepted. :D The old devils, tilted part way on their side in the sidewinder GM bus application, did leak a lot of oil out of the tin valve covers. The aluminum valve cover castings and modern sealants have made the 92 series as leak free as the Allison transmission.

The little electric pump is great where you want to install new fuel filters or replace a fuel line and don't want to wear out your arm on the hand pump. I just tighten the filters until they are about a turn away from seating and hit the juice. As soon as the bubbles stop, I finish tightening. The engine will start like you never touched the filters. All diesel engines have some kind of spring loaded check valve in the return line so they don't loose all fuel back to the tank after they are turned off. The electric pump you put into the system should supply more pressure than the resistance of the check valve so all the air can head down the return line to the tank. I remember Mercedes diesels had a ball with a spring keeping pressure on it at the return end of the Bosch injection pump. After years of service, the ball would get microscopic valleys in it and not keep the pressure up to specs in the interior of the high pressure injection pump. Translation was less power and slower starting due to system leak down as it took a couple more seconds to bring the pressure back up after sitting overnight.

I installed a small pressure gauge on one of the unused ports on the primary filter. When I used the hand pump, I could tell when the pressure reached the check valve limit. Just had to install an electric pump with a little higher pressure. Think it was 12 psi. Pumps always have a spec sheet either in/on the box or online from the manufacturer.

I put an electric pump on my SOB with the Navistar diesel. It's rotary injection pump did not tolerate air. Perkins and Case with rotary injection pumps don't prime well either.

Modifications with resonators, larger turbo, other mods will see a lot more power on the mechanical engines (Cummins, CAT) if the Bosch injection pump is taken to a injection shop and re calibrated for more fuel as well as adjusting the timing for each cylinder. Otherwise, the exhaust temperature drops from more air but you will only see a marginal improvement in power. The engines WILL run smoother afterwards. Bosch only gives several minutes to calibration when the pumps are new and a good shop can always do a better job.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)