Questions about Lift Pump

[LynnandDot]

Our new to us 03 Itasca Horizon 32' DP is equipped with a 300 Cummins ISB. We're hearing horror stories about lift pumps. Not sure what the lift pump does, apparently it moves the fuel from the tank to the engine to the high pressure pump. I'm wondering if we shouldn't carry a spare. Is that something we would get from Cummins, or from Freightliner, or from Winnebego? And where is it located? Enlighten us please.

Lynn & Dorothy & Missy the Mini Schnauzer
Carson City, NV, area

[Ed ke6bnl]

Originally Posted by missymoto

Our new to us 03 Itasca Horizon 32' DP is equipped with a 300 Cummins ISB. We're hearing horror stories about lift pumps. Not sure what the lift pump does, apparently it moves the fuel from the tank to the engine to the high pressure pump. I'm wondering if we shouldn't carry a spare. Is that something we would get from Cummins, or from Freightliner, or from Winnebego? And where is it located? Enlighten us please.

Lynn & Dorothy & Missy the Mini Schnauzer
Carson City, NV, area

do not know much about your cummins ISB but the weal link in my 24 valve cummins is the lift pump, some people carry a spare, if the pump goes the injector pump will try to do the lifting of the fuel for a short time but the lift pump serves to keep cool fuel passing through the IP. I have replaced my pump with an Air Dog very reliable with its own fuel filter and water separator. Might want to contact them about there use on your motor. Not cheap comes with all new line and fittings for my install at about $700 but I do not worry about lift pump issues any longer and I believe it comes with a life time warranty. ED

[H. Miller]

See www.bluechipdiesel.com/injectionpumpfailures.html

[charles tuit]

I have a 02 ISB. I had the lift pump and injector pump replaced at approximately 70,000 miles as the coach hesitated while climing hills or under heavy demand. In my case it gave plenty of warning so it didn't stop us on the road. That was 90,000 miles back and have used a additive since and had had no problems.

Charlie Tuit
02 Journey, 160,000 miles
XL-7 toad

[Wizard]

Charley, what additive and what does it do. Seems your doing something right.

[Gary RVRoamer]

The lift pump gets fuel out of the tank and into the filters and fuel line. It's primary job is to prime the fuel system for easy starting. The injector pump (high pressure) does all the heavy work while under way.

You could carry a spare, but I'm not sure why you would pick that spare part over anything else that might fail. Personally, I just carry spare fuel filters.

The pump is part of the fuel supply system that is installed by the chassis maker, not Cummins. Diesel lift pumps are commodity items - most any diesel repair shop will have them or have a parts source to get them. And of course a Freightliner dealer or Freightliner factory parts could supply one for your Itasca (they use FL chassis).

[RustyJC]

Originally Posted by missymoto

Our new to us 03 Itasca Horizon 32' DP is equipped with a 300 Cummins ISB. We're hearing horror stories about lift pumps.

Even though your MH may be titled as a 2003, depending on the vintage of your chassis, you may have a Bosch VP-44 injected ISB or a HPCR (high pressure common rail) injected ISB. The VP-44 injected ISBs used a Carter lift (fuel transfer) pump that was much more failure prone.

Rusty

[charles tuit]

I don't claim to be a expert on lift pumps but after spending $3,000 on new lift and injector pumps it seemed that adding additional lubrication via an additive wouldn't hurt and maybe prevent another replacement.

Have used Lucas previously and am now useing Opti-Lube summer blend.

Charlie Tuit
02 Journey, 160,000 miles
XL-7 toad

[Ed ke6bnl]

What I use and have since I bought my truck is 1 oz. per gallon of outboard motor oil mix. TWC 3 I purchase it at walmart there brand is the cheapest and I think it is cheap insurance for added lubricity that is no longer in the newer fuels.

[smiller]

If you have the '3rd gen' HPCR ISB engine (generally used from 2003 on) then the worst problem you will probably see from a failed lift pump is a failure to start. Not desirable of course, but hardly a nightmare.

[JJJJorge]

'01 Winnebago Journey replaced a couple lift pumps. ISB 300 Cummins. If the lift pump fails your done. After replacing two lift pumps which are a CUMMINIS part and a dump truck of misery I spent $1500.00 for a After market device. Which was suggested by Rocky Mountain. A complete installation contains a filter also.
The left pump is located near on the left side of engine, all it does is supplies fuel for the high pressure pump. Our fuel was 20'+. The first lift pump failed with-in two months. And the high pressure pump also. (?) I could a write about the event. Towing twice, two lift pump, two VP44 pump replacements, Failure fuel lines. The computer program operating this system failed. We lost all the information such the odmeter. The wiring for the control was hard wiring instead twist pairs, the hard wire failed several times.

[smiller]

It's important to note the difference between the 2003 and later 'common rail' engines and the pre-2003 models. Lift pump failure on the earlier models was a common issue, and when the lift pump failed there was the potential to also damage the very expensive high-pressure pump. On the later engines lift pump failures are less common (although like any cheapo OEM fuel pump they will eventually fail of course) and the inlet pressure of the newer high-pressure pump isn't as critical so usually the pump will not be damaged by a lift pump failure. In the later models when the lift pump fails the high-pressure pump will lose prime when the engine is shut down and the first symptom might to failure to start, but usually nothing worse than that. But the lift pump is more critical on the older engines (as outlined in the previous post) and on these models a fuel pressure gauge is a good idea.

[LynnandDot]

Thanks for all the answers and hints. Now there seems to be some question if it has a Bosch injector pump or a common rail fuel system. Not sure what that means but the numbers on the coach say the engine model is ISB-02. It's serial number if 56966578. The owner's manual says it is a common rail type, but I'm still not sure. Does this mean that the lift pump would be attached to the engine rather than the chassis?

[RustyJC]

Originally Posted by missymoto

Now there seems to be some question if it has a Bosch injector pump or a common rail fuel system.

The following photo shows the Bosch VP-44 fuel injection pump and injector lines (albeit custom ones) for the Bosch VP-44-injected (i.e., NON-common rail) ISB.



Rusty