So here recently my trucks been loosing prime/fuel pressure after its been shut off and sits for a few hours, normally overnight.  The other day it did in the 4 hours from when I got to work and left for lunch.  This really bothered me, so after lunch I crawled all over her and checked all fittings to the fuel system I could get to.  With no luck of something loose, I was not happy and dreading it bein internal.  Pulled the dipstick and with 2k on this oil change, I was maybe a qt over full.  This tells me that Ive got an injector thats leaking down after shut off.  Truck runs and drives fine, no extra smoke at idle or drive, nor does it run any hotter.  So finally to my question.  Is there a way to test the injectors without pulling them out and sending them off?  Can you do a leak down test somehow through the injector tubes?  Also the injectors at 100hp, and if they have to be replaced as a set Im leaning on going to a 125 or 150 hp.

Most likely a bad O ring on the injector. I dont think you can do a leak down test on an injector. Your fuel system bleeds off all the pressure once you shut down the engine any way. I would think with a bad injector you would notice something in the way it runs like a loss in power or fuel mileage or a miss.

 The hard start after sitting is usually a leak somewhere that is letting air into the fuel system after shut down. Two of the main culprits are the return line on the back of the head and the tee it ties into along with the return from the VP. Neither one is easy to see. The head requires a mirror and the return tee is tucked in behind the filter canister at the back of the engine. They dont necessarily leak a lot fuel for you to see.  

 How many miles on your injectors?

Edited May 22, 20177 yr by dripley

2 hours ago, Stanford said:

Is there a way to test the injectors without pulling them out and sending them off?

 

No. All 6 injectors have to pulled and pop tested. There is no test that can be done without removal.

 

2 hours ago, Stanford said:

Can you do a leak down test somehow through the injector tubes?

 

No. Because you need to be able to see the nozzle and if it pissy as you rise up in pressure. It should remain closed till you reach pop pressure. As injectors wear the pop pressure gets lower and the injector becomes pissy. 

 

2 hours ago, Stanford said:

Truck runs and drives fine, no extra smoke at idle or drive, nor does it run any hotter.

A failed injector(s) don't normal change in smoke or anything it might get a random misfire but not always. As pop pressure falls it just advancing timing. The spray quality might degrade and it might not. All depends on the failure.

 

1 hour ago, dripley said:

Most likely a bad O ring on the injector.

That's possible for the growing oil but would explain the loss of prime because the oil would seal the leak after the pressure faded. Crossover o-ring could produce a loss of prime but typically the manifold would be moist or wet with fuel from the leak. 

Edited May 22, 20177 yr by Mopar1973Man

1 hour ago, Mopar1973Man said:

That's possible for the growing oil but would explain the loss of prime because the oil would seal the leak after the pressure faded. Crossover o-ring could produce a loss of prime but typically the manifold would be moist or wet with fuel from the leak.

I was just addressing the growing oil with the bad O ring and not the hard starts. Your'e still a pretty smart feller though.

Time for a paper towel test with the oil.

How does the paper towel test work? I changed the oil last night before I drove the 20 miles home and still have it sittin here. Also I checked the oil this am and it's over full. Not surprised there, but was a little by the amount over.  There's no fluid on the manifold or anything that would make me think it was the crossover tubes. It turns over crazy fast like there's not a drop of fuel in it.  Not sure there's anyone around here to can pop test the injectors. Tryin to figure out if it's worth the labor to pay someone to test them or just buy new and get it done.  These injectors are around 5 years old and probably has somewhere in the 60k like range.

Do you guys recommend new tubes with new injectors? Looking at goin with DAP new bodies.

i am on my 3rd set of injectors with the oe crossover tubes and they still seal just fine. I have read here in the past that some of the earlier 24v's have different tubes and the dont hold up as well. I dont know that to be a fact however.

I use the dip stick to place a drop of oil on a piece of white paper towel. Do not need much. Looking for a fuel ring around the outside of the drop.

That's kinda what I figured on the test. It's definitely lighter around the outside of the spot I put on there.

1 hour ago, dripley said:

i am on my 3rd set of injectors with the oe crossover tubes and they still seal just fine. I have read here in the past that some of the earlier 24v's have different tubes and the dont hold up as well. I dont know that to be a fact however.

3rd set? Change your mind or have you had problems with them? I really didn't think I'd ever have an issue with this set, but as I look back I got the aftermarket bodies and not the new bodies. Not sure if that hold true or not

1 minute ago, Stanford said:

3rd set? Change your mind or have you had problems with them? I really didn't think I'd ever have an issue with this set, but as I look back I got the aftermarket bodies and not the new bodies. Not sure if that hold true or not

I changed my oe injectors out near 250k miles for a set of RV275's. I changed the RV's out with about 140k miles on them thinking I might have one going bad. Turned out not to be the issue. But i did want to try out something different and put in a set of 50HP DAP injectors with after market bodies. They work fine but a bit smokey. I their defense though I do have some boost leakage which is not helping. Hope to rectify that very soon and will see how they do. I have 10k miles on them at the moment. So to answer your question, I have not really had any problems with any of them, just experimenting.

Are you sure it isn't coolant making its way into your oil?

15 minutes ago, Hawkez said:

Are you sure it isn't coolant making its way into your oil?

Yeah, oils not milky in anyway

There is only one other place for fuel to enter the crankcase which is the front seal of the VP44. Typically this could happen of the fuel pressure is driven well above 20 PSI on a weak or worn front VP44 seal. Most typically though the bad injector is the cause of the fuel in the oil.

I've never seen anything above 20 psi since I've owned it. Think for the price to get the injectors tested and the time down to send them off and wait, I'll just buy new and get them swapped. Wife's not goin to enjoy only one car for the next couple weeks, lol