bus pump low power?

F

fummins97

New member
Joined
Sep 15, 2008
Messages
215
Hello, I've done some reading and pretty sure I've got my answer, but just to get a straight answer...... is there any difference between a school bus p7100 (230hp) and a dodge pickup p7100? Overall reason for question is I have a issue with my truck where it just does not feel like it has any power and there's very little boost. Specs are 95 Cummins (from dodge truck), bored .040th's over to 6.0, enterprise engine kit, bus p7100, non stock fuel plate, turned up boost screw, torkteknology 50hp overflow valve, 5x14 injectors, 64/74/14 II Silverbullet. Boost gauge is only hitting around 15psi. Truck is a 97 CCSB F350 with e4od trans, banks billet torque convertor and 3.55 gears. I'm also having issues with the PCS trans controller, so maybe the trans is holding the engine back also, but for what the engine has, I can't believe it shouldn't be more powerful.
Just looking for some ideas as what to check, or maybe something wrong in the pump. As far as I can tell I don't have any boost leaks either. Thanks for reading.
 
Have you checked for boost leaks with a boost leak tester? How about your fuel pressure? Your lift pump could be getting weak or you have a boost leak limiting your AFC from giving full fuel. You could try removing the AFC foot and see if it will build more boost. If so you have a boost leak to track down.
 
most bus pumps are 11mm versus dodge 12mm, but with 5x14 should still be rolling.
 
describe your fuel supply system from tank to P7100. is it airdog/fass or still oem? there are a ton of common problems with oem so ill wait till you respond.
 
do you have a fuel pressure gauge? egt gauge? if so give us more info on temp and pressure
 
Levi_plummer said:
Have you checked for boost leaks with a boost leak tester? How about your fuel pressure? Your lift pump could be getting weak or you have a boost leak limiting your AFC from giving full fuel. You could try removing the AFC foot and see if it will build more boost. If so you have a boost leak to track down.
Click to expand...

no not with a tester. I will try removing the foot.

mike_belben said:
describe your fuel supply system from tank to P7100. is it airdog/fass or still oem? there are a ton of common problems with oem so ill wait till you respond.
Click to expand...

bdp fuel sump, 1/2" lines, a1000 pump, filter, to pump.

mike_belben said:
do you have a fuel pressure gauge? egt gauge? if so give us more info on temp and pressure
Click to expand...

just put in a egt gauge but it isn't working so need to fix that. Looking to get a fuel pressure gauge but not sure on mechanical or electric. My other two gauges are autometer ford factory match, so the fuel pressure is electric, had a friend tell me mechanical is the only way to go. What's the general opinion on electric?
 
I'm running an electric Autometer fuel pressure gauge with the sensor in the dual feed tee to the p-pump.
 
Howling said:
I'm running an electric Autometer fuel pressure gauge with the sensor in the dual feed tee to the p-pump.
Click to expand...

I've never had one on either diesel, so when I get it, where and how do you mount the sensor? What type of a tee is needed?
 
I'm betting it is a P3000 11 MM pump just like the one I bought a while ago. Send it to Seth to have him flow/max/balance it, he got 280CC out of mine IIRC.
 
06 DIESEL said:
I'm betting it is a P3000 11 MM pump just like the one I bought a while ago. Send it to Seth to have him flow/max/balance it, he got 280CC out of mine IIRC.
Click to expand...

He got 350 out of mine but set it to 280.
 
06 DIESEL said:
I'm betting it is a P3000 11 MM pump just like the one I bought a while ago. Send it to Seth to have him flow/max/balance it, he got 280CC out of mine IIRC.
Click to expand...


According to the tag it is a 12mm P7100.

There are a few different variations. The last one I had was a 190hp pump with 12mm flat top plungers and the 160/175hp d-shaped cam profile. Everything I found online suggested that that 190 pump should have had the 215 style plungers with timing retard notches.
 
bna5017 said:
According to the tag it is a 12mm P7100.

There are a few different variations. The last one I had was a 190hp pump with 12mm flat top plungers and the 160/175hp d-shaped cam profile. Everything I found online suggested that that 190 pump should have had the 215 style plungers with timing retard notches.
Click to expand...

I also have a 190hp pump out of a 1997 bus. It deffinately has the retard notches in the plungers. I don't have an issue with fueling though.
 
Gov springs and timing? I know some of the bus pumps had lower/different governors. I'm not sure where to look on the tag, but hopefully someone will chime in. Your setup is similar to mine and my truck moves!
 
timing is at 18*, stock gsk and valve springs. Would a normal 4k gsk work in my pump IF it is the 11mm?
 
fummins97 said:
timing is at 18*, stock gsk and valve springs. Would a normal 4k gsk work in my pump IF it is the 11mm?
Click to expand...

Yes, but unless someone has swapped the plungers and barrels, it is a 12mm pump. I suspect an upgrade in the governor spring department will be a big help. Talk to Seth at Farrell diesel service about governor springs, his 5k's drive far better than my old pac brake 4k kit did.


I have read on the interwebs about this bus pump governor, but have been told it is a myth.
 
bna5017 said:
Talk to Seth at Farrell diesel service about governor springs, his 5k's drive far better than my old pac brake 4k kit did.
Click to expand...

Not to hijack, but how does it drive better? I like my pacbrake springs, but I never stop trying different mods.


I haven't driven one with stock gov springs, but upgrading the gov spring on my first gen made a night and day difference.
 
You must log in or register to reply here.
Top