is this the right place to check fuel pressure on a cat 3304di engine. It is in a cat 215 95z00480. It shows no pressure when engine is running, Shows pressure using primer pump, engine off. gauge fittings are not leaking fuel out.
Yes. Should be 30 to 40 psi Should be mechanical transfer pump on side of fuel pump.
Thanks. Do you have any idea why engine runs but shows no fuel pressure? Would close to zero pressure be enough for engine to run at a decent rpm but have not a lot of power?
That engine doesn't have a pressure relief valve in the return line does it.? Isn't fuel pressure maintained by a return line orifice in the pump.? Can't see something like that getting screwed up but there's always a first time I suppose. Have you tried running the fuel return line into a bucket just to see what sort of fuel flow is coming back to the tank.?
Isn't that where the bypass valve belongs?
The 4S6526 Spring is not listed for the engine of anything 95Z-prefix.. SysOp schematic shows a constant bleed orifice #11 in the return line at the FIP outlet.
Yes I think that there is a return line orifice in the pump, seen it on the drawing. I have not ran a clear return line into a bucket. I imagine that if there is in fact very low to zero fuel pressure that there will not be any fuel returned to the tank, that sounds like a good test to run.
If it's possible to disassemble the fitting on the return line outlet of the pump it might be worthwhile tearing into it just to see if the orifice is in fact there at all.
I recall another thread with a discussion relating to that orifice and I think I spent a lot of time trying to find any information other than the "Systems Operation" drawing that is shown int Post #6 above. I'm wondering if this "orifice" is not a separate part but simply a hole bored in the pump casting. I even did a keyword search for the serial number of the machine and it finds some but none related to the fuel system.
Why not disconnect the return line and run the engine? If the supply pressure is near zero, the return volume will be minimal. If the return volume is large, we'll have to help you figure it out.
I pulled return line and ran engine there was very little fuel dripping from line at times and most of the time there was none. If I pump the primer I can get it to come out with engine off. My fuel pressure gauge does work when I pump the primer with the engine running or not. I can build the pressure up to 15 psi or so and it will slowly drop when I quit pumping. I am going to pull the transfer pump and have a look inside of it.
Nige thanks for the reply, I removed the fuel return fitting on the pump and found nothing there, just a regular fitting. Kshansen thank you for investigating that orifice in my other post, I am still trying to resolve the same problem with this machine. As for your thought about it being just a hole bored in the pump casing I think you may be on to something. I pulled the pump off and disassembled it, the casing is aluminum and there is a steel sleeve that the piston rides in, at the bottom of the stroke there are two holes where fuel bypasses and is directed to the return lines that head back to the tank, this may be the elusive constant bleed orifice. I did find that two of the three check valves inside the pump are in bad shape and is definitely the cause of the low fuel pressure, hopefully it is also the cause of the low power issue also. I am going to change or rebuild the transfer pump and let you guys know how it turns out.
A process of elimination basically. If whatever is supposed to restrict return line flow is in place and is working as it should then the focus falls on the transfer pump failing to build pressure. I show a complete pump at $550, a Reman at $420, and piece parts like the check valves and o-ring seals all appear to be available. Do you have a Parts Manual..?
No I do not have a parts manual. I see aftermarket pumps online for around $100, any good? Or go with a cat for around $500. Rebuild kit is about $50 aftermarket.
I’ll post the parts breakdown later. Cat don’t appear to do a repair kit, it’s all shown as piece parts, although you could ask the dealer if a kit is available. TBH I’d have a Reman pump @ $420 if I was going for a complete pump.
Reman number is OR3537. Just as mentioned in another thread make sure you reassemble the pump and return in box the reman one comes in or else you could get charge a $136.00 core charge
Here's the complete parts listing. I am not 100% certain this is the pump from your machine. See if you can find any Part Number on the body of the transfer pump that approximates to 1W-1698, that would confirm that it is the right one. There is an o-ring on Page 1 to mount the transfer pump to the FIP. Don't count on it being in the box with the replacement pump if you go that route. Try pricing individual parts before you make a decision which way you are going to go.
You can download a Parts Manual in pdf format from Cat for $89 by following these instructions. Got to https://catpublications.com/ Click on "Continue as Guest" Type HEBP1427 in the box and click "Search". You should see the illustration below.
Take it to a fuel shop.. If I had a dollar for every valve we didn't put in 1 of those pumps, I'd have A LOT of dollars.. Lol They'll have the parts.. just laying around..{from old kits} Ask them if they do 3304 pumps THERE.. U hafta specify "THERE".. because its getting to the point now that a lot of these shops are just "drop-off" spots & then they send'm out to get rebuilt..
That is a common failure on these transfer pumps. 3 new check valves and seals and you will definitely have more power. It would have been barely running with 0 psi fuel pressure.
Check valves are listed @ around $5 each. Add a few o-rings and seals to that and you could probably rebuild that pump for less than $50 in parts.
There have been some changes in those three check valves. If there is no major wear in the piston or sleeve you should be able to replace all the seals and check valves for something like $30.00 Actually just checked and my price for the seals and check valves come to all of $26.14 which might include a bit of corporate discount but would not expect much on that small an order! Would need to do some good cleaning and checking for wear in the piston, plunger and sleeve areas. But if they look pretty good I'd be confident it would end up with much better than ZERO psi!
Here's the parts breakdown on the 1W1695 pump, yes I know it says something about D7 but this one shows what should be the latest valves and seals. In addition to the seals listed in the attachment one would need a 4J8997 seal to mount to the side of injector pump.