Leaking Injector?

[98TxTJ]

Began having intermittent long crank issues in the last two weeks. Sometimes when cold, sometimes not. More often when hot.

Fuel pump is a Delphi installed just shy of a year ago. I thoroughly cleaned the fuel tank at the time.

Put a pressure tester on today. Right at 50 psi with engine running, but it drops like a rock as soon as you shut off the engine. Normally that indicates a failing check valve at the fuel regulator on top of the pump.

BUT, I clamped off the supply line after pressurizing the rail, shut off the the engine, and the pressure still drops to zero immediately. Per th e manual, this could be a leaking injector.

No codes, no misfires, no rough ide.

Thoughts?

 

[pagrey]

Pull the injectors or fuel rail, if they are leaking you'll see when you cycle the key. Done and done.

 

[98TxTJ]

Pull the injectors or fuel rail, if they are leaking you'll see when you cycle the key. Done and done.

Thanks. It's on tomorrow's agenda. If they are leaking probably should do an oil change right away, huh?

 

[pagrey]

Nope, it takes a hell of a leak to mess with the oil. I'd just check them and go from there.

 

[98TxTJ]

Question part 2:

Replacement recommendations?

 

[pagrey]

If I had a single leaking injector I might just get a crap replacement from rockauto.com for about $25 and see if it fixes it. On the other hand if I was in for the long run, I'd get a matched, cleaned set on ebay from a place that does that stuff. I lean cheap if you can't tell.

 

[03coloradowrangler]

I recently just lost a Delphi pump check valve on a pump which was a few months shy of a year.

had excessive cranking and hard starting problems which suddenly appeared.

I agree. buy new injector orings (to replace now that you're pulling the injectors), pull the injector rail from the manifold and key on to pressurize fuel system and see if leaks occur at injector nozzles after keying off. if no leaks id expect the pump. im intending to buy a Bosch pump now that they are available for my 03 again and get rid of the warrantied Delphi I had to reinstall.

when I tested the pressure I had 0 at key on, very slowly built up pressure to around 49/50 after cranking ~8-15 seconds eventually sputtering and starting like crap. maintained about 49/50 psi when running then immediately 0 psi after shutting off engine and sucking air when I pushed in the fuel rail Schrader valve core. I was able to replicate this issue each time I started it while watching the fuel pressure gauge. replaced the pump and had been fine but now its been a couple weeks since installing the warrantied Delphi pump and again im beginning to have awkward starts again while the engine is both cold or warm and suspect its the Delphi pump again. its slightly hesitating again after a normal amount of time of cranking.

 

[Mariposa Mike]

I'm brand new to the forum but have been reading about the starting issues because I'm having those as well. I have a new to me 2004 Unlimited with only 8,000 miles on the clock. The previous owner advised of trouble starting and I read the earlier submissions on this site related to the problem. The Jeep obviously sat a lot and I expected fuel issues along with the coolant being rusty. Another story. If I can join into this discussion and add that on mine the starting issue has gone from bad to worse and stumbles a lot on start up but runs fine after that. So I suspect the pump and pressure regulator but should I also be looking for a leaking injector? Seems with such low mileage that would not be the case but advice would be appreciated. I do not have a rail pressure tester but may have to get one.

 

[pagrey]

Low mileage can definitely be a big liability, things don't like to sit. You might run a tank of techron though it the next tank. After that here's what I'd do. Cycle the key several times on cold start to prime the pump and see if that helps. If it starts easy you know you are just loosing pressure. Then I'd buy new injector o-rings and pull the fuel rail, it isn't too difficult. Prime the pump again and see if any are leaking. If they hold fuel then i'd replace the pump assembly. I've been able to fix my start issues that way without resorting to a fuel pressure gauge although with an adapter it's not difficult to hook one up.

 

[Mariposa Mike]

I added a bottle of Techron and my first and only fill so far was the Chevron fuel. At first i thought the problem was likely fuel varnish in the pump or a clogged screen. Also tried the turn the key several times. Makes no difference. I can hear the fuel pump working so figure its something else. Runs great on the highway. No indication of fuel shortage. Everything points to the fuel pump or the pressure regulator but the stumble when it starts makes me suspicious of maybe another problem.

 

[98TxTJ]

If I had a single leaking injector I might just get a crap replacement from rockauto.com for about $25 and see if it fixes it. On the other hand if I was in for the long run, I'd get a matched, cleaned set on ebay from a place that does that stuff. I lean cheap if you can't tell.

No joy. Pulled the fuel rail, disconnected the injectors and cranked the engine. No evidence of a leak.

I took all the injectors out and cleaned them up, then coated the o-rings with silicone grease before reassembly.

A word to the wise: It looks like the line connected to the fuel rail has a flexible hose section you can clamp to isolate the rail from the line to the tank. DON'T DO IT.

The hose looking part is only a cover for a section of semi-rigid plastic line inside. When I clamped it to test last night, I wasn't getting a tight seal and I squashed and deformed the plastic line. I slid the cover out of the way and checked for cracks visually and when pressurized. No sign of a leak due to damage of that section, but I think I will replace it.

Bottom line: I didn't have the correct fittings to isolate the incoming fuel line so I could pressure test just the rail, but based on the cranking-with-the-fuel-rail-out test, it's probably the pressure regulator on top of the fuel pump that is allowing the leak-back.

Also, for those of you doing pressure testing, it is normal to have zero pressure on a cold engine that has been sitting. The service manual mentions this several times. If there are no leaks, fuel is still in the line (it will dribble out the Schrader valve when you press in on the pin), but not under pressure.

When you test, if the pressure stays above 30psi for 5 minutes after turning off the engine, the service manual considers that a passing leak-down test.

 

[pagrey]

Everything points to the fuel pump or the pressure regulator but the stumble when it starts makes me suspicious of maybe another problem.

You are cycling the key many times to build pressure and not test the pump if that makes sense. The check valve doesn't keep pressure like it should if it is leaking and cycling the key can help but sometimes the check valve can be shot to the point pressure simply bleeds too fast for the key trick to work. You might look into hooking a fuel pressure gauge up to it, no guesswork at that point. If it runs fine at speed I wouldn't suspect the regulator or fuel pump, just the check valve.

No joy.

Sorry about that fuel line thing, doesn't sound fun. Looks like you're pulling the tank, that's no fun either. I've pulled my tank more times than I'd like to admit, on the bright side it gets easier.

 

[Mariposa Mike]

Is the check valve in/on the pump or outside the tank on the engine? I agree I probably need to get the pressure gauge to avoid just throwing parts at this problem. Also, looking on Amazon I see a Bosch 69316 pump (which I probably don't need but when I look at pressure regulator it says it's not deliverable to my location and to pick another location. Does that make any sense? Can't imagine a part would be banned in Kalifernia if it's like an original. So it seems there is a check valve, pressure valve and a fuel pump in this process of delivering fuel. Is that correct?

 

[Wtrask]

I had the exact same issue. I replaced my injectors with remains for like 100 bucks off eBay. I pulled the fuel rail and pressurized it. I had 3 injectors leaking fuel.

 

[98TxTJ]

Is the check valve in/on the pump or outside the tank on the engine? I agree I probably need to get the pressure gauge to avoid just throwing parts at this problem. Also, looking on Amazon I see a Bosch 69316 pump (which I probably don't need but when I look at pressure regulator it says it's not deliverable to my location and to pick another location. Does that make any sense? Can't imagine a part would be banned in Kalifernia if it's like an original. So it seems there is a check valve, pressure valve and a fuel pump in this process of delivering fuel. Is that correct?

The service manual implies that there are two check valves. One is in the fuel regulator that sits on top of the pump, the second is in the pump body itself. Quote from the manual:

"A quick loss of pressure usually indicates a defective check valve in the filter/regulator. A slow loss of pressure usually indicates a defective check valve in the electric fuel pump."

 

[pagrey]

Those pumps can be difficult to source, no California restrictions on them. I think the valve is in the pump and not in the filter regulator at the top but I don't know for sure. I've always replaced it as a complete assembly. Somebody else will chime in or you can search other threads, it's been answered before (looks like @98TxTJ has it covered).

So it seems there is a check valve, pressure valve and a fuel pump in this process of delivering fuel. Is that correct?

I think it's lower screen, pump, check valve, up to the top of the tank, regulator and return, upper filter, on to the engine, but there might be another filter or screen in there somewhere.

 

[Mariposa Mike]

So once I get my readings if the loss is slow does that mean one can buy a part for the pump or is it buy the entire pump?

 

[Mariposa Mike]

By the way, thanks for the replies. I have a decent knowledge of mechanics but mostly on things that throw codes or diagnosing older vehicles. Know nothing about these newer jeeps but restored a 1961 M38A1 and have a modified 56 Willys wagon. That's the extent of my Jeep experience.

 

[Mariposa Mike]

I plan to purchase a pressure gauge but looking at the engine I'm not sure where it hooks into the rail. I see a connector to the rail for the delivery of fuel and it appears to have a disconnect that might require a tool as well. If that is the case then I need to look for that unless it comes in the kit. Does anyone know if it requires a special tool to disconnect and if that is the place to check pressure? Will order the tool(s) today if I can get the info and maybe which company makes the better gauge.

 

[03coloradowrangler]

typically if you go into your average local autoparts store (big chain) they have tools you can loan if you put a deposit down. I loaned the fuel pressure tool I had used from one and returned it for full refund.

as for where to tap on your setup, ive got no idea. luckily my rail had a Schrader valve to screw the pressure tester onto. at one point on this website I seen a how-to on how to fabricate a adapter to add a pressure gauge inline to measure the pressure on a rail without the Schrader

as for the special tool required to disconnect the flexible fuel line from the rail you'll need a toolset called a "fuel line disconnect toolset" Lisle makes one, part number 37000. this too may be something you can just walk into your local auto parts store and purchase or possibly loan. ive never looked as I have had a set but it may be avaliable too.

the correct size just slips over the fuel rail side of the line and pushes into the flexible side fitting releasing the inner lock clips and allowing the fitting to pull off the rail.