CAT 3306 engine starts then dies out - primer pump has resistance B/4 engine starts t

I could use some help. On the CAT 3306 engine I prime the fuel system and there is resistance after a few pumps on the primer plunger. The engine starts, but after a few seconds it dies. Go to push the primer again and there is no resistance until I push a few times, then engines is able to start again, than a repeat the engine stops after a few seconds of running. Any ideas, this is the first time it has happened. Engine arrangement 6N1309 Engine Serial Number 66D14810 Model 3306 250 HP Fuel priming pump is CAT # 4N4314 N/S pump assembly # is 4N2511

Those cat primers are known to suck air. How old is it? Does it eventually get running or does it keep dying? Have you tried priming it while somebody cranks it? Sent from my iPhone using Tapatalk

If it runs while pumping primer then i would inspect transfer pump.

Sounds like you got no flow from tank to transfer pump..

^^ yeah, like something blocking the tank outlet to the pump, it doesn't take much debris to block it so it will not run but yet it will still start... I have had this happen to me several times with different equipment.

If that's the old style pump with the umbrella seals on the drive shaft, they go bad and will suck air sometimes. 66D is industrial as I recall, is it in a gen set, water pump, Morooka dumper, or?

Check the fuel pressure when it's running at the top of the secondary fuel filter. The transfer pump is a gear pump in the front part of the fuel injection pump. The fuel injection pump will have to be removed to service it.

Mobiltech said: Check the fuel pressure when it's running at the top of the secondary fuel filter. The transfer pump is a gear pump in the front part of the fuel injection pump. The fuel injection pump will have to be removed to service it. Click to expand... Before pulling the pump I'd try pulling the plate off the side of the injection pump. Remove the fuel filter head that shows in you parts picture. Under this cover is a check valve and a pressure by-pass valve. Check valve item #7: By-pass valve goes in hole just to the right of check valve: I'd probably just get the cover gasket and gasket or seals for filter head and the two valves and the spring for the by pass valve before opening it up. Just make sure everything is spotlessly clean before opening it up. There is a small part on the back side of this plate called a channel with gasket part number 4N4431 you might also want to get. All the gaskets seals and the two valves should be about $30.00

Ronsii said: ^^ yeah, like something blocking the tank outlet to the pump, it doesn't take much debris to block it so it will not run but yet it will still start... I have had this happen to me several times with different equipment. Click to expand... That's my bet. Or a blockage somewhere else along the line. Testing the pressure will tell you which direction to look. Or you could start in the middle with a pressure test, or at the inlet. It should be easy to find if it dies right away.

Just thinking about this 3306 again. It was mentioned that this is the first time it has done this, so I'm assuming this was running good before? What was done to it since the last good running time? maybe changing fuel filter? Isn't there a bleeder valve on the pump just in front of the fuel filter? If so if this is opened can you pump a good stream of fuel through it with the hand pump? Crazy thought but is there a shut off valve in the line to the pump that was turned off and not turned back on after changing filter? How about eliminating most of the fuel supply system? Connect a couple lines from fuel pump to a five gallon pail a few feet of 1/4 fuel hose and two barbed fitting installed in pump. Then see if it will start and keep running, if that works then you know the engine is not the problem and problem is in tank and lines to it.

Today I tried priming the engine again and fuel came out of the primer pump tripping onto the ground each time I pushed the primer in and out. I am thinking the gasket needs to be replaced. Also noticed on a fuel gauge mounted on a fuel line directly above the primer pump that I can pump the pressure but it right away drops off to no pressure. look at photo; lower right corner is the primer pump above it is the fuel gauge.

Probably needs the whole primer, not just the gasket Sent from my iPhone using Tapatalk

Is that Tee handle under the gauge turned in tight? When priming that tee is open until fuel flow's out and the turned in (off) and keep pumping, the gauge should act different with the tee totally closed. Closed is the run position also.

grandpa said: Is that Tee handle under the gauge turned in tight? When priming that tee is open until fuel flow's out and the turned in (off) and keep pumping, the gauge should act different with the tee totally closed. Closed is the run position also. Click to expand... I do not recall but will check it Tuesday morning. Thank you for the comments much appreciated.

Tried it. The tee handle was closed tight. I did open it and pumped the primer plunger fuel poured out of the bleed off line onto the ground; then closed the tee handle and pumped again same thing fuel drips out of the primer, well its more then a drip a teaspoon each time plunger is pushed in. And I still can here the fuel draining off in the fuel line back to the fuel tank. Appears lowest cost is to replace primer and see if that repairs the problem. Any comments???suggestions???

the whole priming pump is very cheap.Better to completely change it instead of just the gasket.They can give you more hassle than you think

Have you had the primer off Bob? Like stated earlier their is a small button type check valve... I had one last fall that had just popped out of it boss... glued it in and its still working.... checkit out.

grandpa said: Have you had the primer off Bob? Like stated earlier their is a small button type check valve... I had one last fall that had just popped out of it boss... glued it in and its still working.... checkit out. Click to expand... Not yet primer still on it, looks like next week work. Bob

Ive had 3 of those primer pumps that were bad right out of the box over the years. They had checkvalves that were tight but would leak bubbles around the perimeter of the valve disc. So just because its new, Dont trust it.

If it is the same pump as my D6C 69J and appears it is, it has no return to tank line. excess pressure from the gear fuel pump is dumped into the inflow gallery. Mine rolled the seal out and was dumping out the drain line between the gear pump and engine mount. Someone had installed a plug in place of the pressure regulator valve and it was blowing seals out and would start, run for few seconds and die. I replaced the valve (plastic) and all side gaskets and front seal from Cat for $45 and fixed the problem. I had also run a rubber 3/8" fuel line into a Goldenrod fuel tank filter and it drooped into a SLIGHT pinch point which would keep it from developing full power, so they take a full stream of fuel at full tilt.