Luca cav dpa fuel pump on perkins diesel

Shaun Williams · Jun 7, 2014

I am having trouble with my Lucas CAV DPA injection pump on a 4 cylinder Perkins diesel in a Clark C500 forklift. Truck was parked for over a year, replaced the starter & it cranked up immediately. Did some preventive maintenance which included changing fuel filter. Bled the lines, etc. The truck would not run. Began looking online & it seems that it was plumbed wrong. Pressure side of filter was going in the return side of the pump??? Replumbed according to diagram online, bled & truck will crank immediately as long as I leave the top bleeder screw loose on the fuel pump & let it spray fuel. As soon as I close the top bleeder, it begins starving for fuel & shuts down. Open top bleeder again & it runs like a champ. Is this a fuel pump issue? I have already changed the filter twice just to make sure I didn't do it wrong.

Steve@Advance · Jun 7, 2014

Sounds like either the fuel transfer pump diaphragm is bad, putting air in the system, or there is a leak in the suction line between the transfer pump and the tank.

thepumpguysc · Jun 8, 2014

I"v seen this about a million x on a Perkins engine..
The Oring "looks like" it fits ontop/inside of the filter..right?
It doesn"t go there!! IT HAS TO GO "up in the filter head", then the filter sandwiches it in..
IF you look closely, you"ll see if you put the oring ON/IN THE FILTER, it blocks the holes..
Good luck and let us know..

Shaun Williams · Jun 8, 2014

I was told that I had the filter head o ring in the wrong place by a really good diesel mechanic too. That's why I went ahead & changed the filter again. However, I'm not above doing it again just to make sure I have it correct. It has acted the same way both times. The strange thing is that it actually runs best with a leak. I had a decent size leak around one of the banjo washers & it runs great. I snugged the fitting some, stopped the leak, & it chokes down almost immediately. If I indeed do have air being introduced into the system, what is the best way to find it? Just to throw out more info, it seems as tho the top half of the fuel injection pump is running out of fuel because if I crack the bleeder just before it chokes down, it will blow a bunch of air out then start blowing fuel out & catch right up & run perfect. I genuinely appreciate everyone's help on this btw.

thepumpguysc · Jun 9, 2014

I to have seen them plumbed wrong and work fine..
and when I change them they wont run..??
I haven"t figured that one out either..
Did you remove any of the steel lines from the filter head or pump?? They have rubber grommets on the end of them and one may have gotten split or crimped.

Dieseltech · Jun 9, 2014

I'm not sure on your application but on MF Perkins tractors there is a constant bleed fitting on top of the filter base that must be open. If plugged any air that gets into the base can't get out, so it goes to the pump inlet, shutting it down. Would be worth a look, may be a banjo or straight fitting, usually running back to the tank tied into the injector top return line. Also if CAV filters are used the extra O ring is not a problem, like Wix or NAPA, as the fuel flow through the filter is different. I've made service calls on the wrong O ring placement too. CAV 296 or 796 filters, no trouble.

Shaun Williams · Jun 9, 2014

I think I got the problem fixed with the help of your suggestions. When I originally found that the fuel system was plumbed wrong, I only switched the lines that were going to the injector pump from the filter housing. Tonight, I switched the lines from the tank to the filter housing, which in turn, forced me to switch the lines again going to the injector pump in order to get the pressure line going into the back of the pump. I bled the system the same way I was doing before and the truck started up immediately, just as before. Except this time when I closed the top bleeder screw, the truck never missed a beat. My guess is that by only swapping the lines going to the injector pump, I created a "dead head" effect and the fuel used to lubricate and cool the injector couldn"t return to the tank? Does this sound accurate to y"all? Either way, I sincerely appreciate the help. Your suggestions got me thinking outside the box and helped me get the truck running again. Can"t thank y"all enough.

Luca cav dpa fuel pump on perkins diesel

Shaun Williams

New User

Steve@Advance

Well-known Member

thepumpguysc

Member

Shaun Williams

New User

thepumpguysc

Member

Dieseltech

Well-known Member

Shaun Williams

New User

Similar threads