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Tons of bubbles in my fuel return line, is this ordinary?
1st Gen. Ram - All TopicsDiscussion for all Dodge Rams prior to 1994. This includes engine, drivetrain and non-drivetrain discussions. Anything prior to 1994 should go in here.
Not yet. I replaced the injectors last week but it's still blowing bubbles during starting. I have a rebuilt injection pump coming in next Tuesday..
Now it's only down the street near friendly neighbors. I appreciate their patience!
Sorry I missed the earlier question. Before I committed to ordering the injection pump I had an electric fuel pump pumping through a clear line directly into the injection pump. I had removed the line between the filter bleed and pump and put the hose directly on. Doing this I pumped clear fuel through the injection pump out of a gallon jug. It took a long time to flush all remaining air out of the pump but after some minutes the bubbles stopped and only clear fuel came out of the fuel return banjo drain line connection. Then I tried turning the engine over and again the bubbles started. After installing new injectors last week thinking one was allowing compression to push back into the pump no symptoms changed. I found a pump in Salt Lake by a guy with a 100% positive feedback on Ebay for under 800. This is a bit convoluted but if it is the injection pump that failed so suddenly I'm surprised I don't see more when I look over the other threads. Safe motoring everybody, Have a fun weekend!
Suction side fuel leaks can be hard to find as you already know. I read the thread but may have missed it but have you tried putting some compression into the fuel tank to see where it’s coming from? It’s worth a try even if you can think of a logical reason for it to not work. There are some things not logical on these trucks…Mark
I have now installed a rebuilt injection pump. It was $775 via Ebay from an outfit with 100% positive feedback. Beautiful pump with all new bolts showing.
Here is a note I sent to the builder asking for help...
Hi, I bought a rebuilt injection pump from you last week. I installed it this morning and I have the same symptoms as before. I am hoping you can give me some clues. I have a electric fuel pump near the tank and it pushes fuel into the stock engine mounted fuel pump. I have installed clear fuel lines going into the engine mounted pump and on the fuel return line on the pump. My big symptom is there are bubbles in the fuel return line coming from the injection pump when I push clean fuel into it. This is without turning it over. Turning it over blows even more bubbles out the return line. It tries to start but only fires on a couple of cylinders and won't catch. Have you got any clues what this could be? I replaced the injectors before I changed the the injection pump but no change there either Thank you!
I find it quite odd that bubbles come from the return line when pumping fuel into the injection pump at rest. And they increase on trying to start it. WTH?
I will try bypassing the engine lift pump and filter next by pumping fuel directly into the injection pump.
Ideas ??
Suction side fuel leaks can be hard to find as you already know. I read the thread but may have missed it but have you tried putting some compression into the fuel tank to see where it’s coming from? It’s worth a try even if you can think of a logical reason for it to not work. There are some things not logical on these trucks…Mark
I figured having an electric pump back at the tank was the same as pressurizing the tank. It makes about 3 psi. I get no air by bleeding the banjo bolt at the fuel filter on the manifold.
I believe that liquid pressure (electric fuel pump) will not have the same result as a pound or two of AIR pressure directly into the fuel tank. You seem to have covered a lot of things trying to find how air is getting into your system and logic says that there is an air leak somewhere. It doesn’t take very long to do and will give you some data at the very least. Imho it’s worth a try, good luck Mark
edit: also your leak could be between the electric pump and the fuel tank.
So you have installed a new "rebuilt" injection pump and are still having the same issue? Does your stock lift pump work? if so try using the gallon jug directly into your stock pump and bleed your injectors using that, if it starts and runs you have a leak somewhere between the pick-up tube and where it hooks to the lift pump. How much fuel is in the tank, as there could be a hole in the coiled line in the sending unit. for pressurizing my tank I used a old cap and took it apart and drilled a hole in it and installed an air fitting in it.. everyone said no more than 5lbs of pressure but I wound up using 10 to make the leak in my line show up .. I hope this helps
Geez, I'm still at it and still broken down. I got the rebuilt injection pump and have installed it . I also replaced the engine mounted fuel lift pump. I got the engine running but only poorly. It would not rev up and would barely idle. It is blowing blue smoke and sounds rough. Symptoms remain the same in that ,,,With the engine at rest, stroking the lift pump priming lever pushes fuel and bubbles out the return line on the injection pump ( I have a clear vinyl line installed so I can watch for bubbles). I can pump for minutes and the bubbles keep coming. I bled everything twice and got it started but only poor running and tons of bubbles in the return line.
I am running out of ideas of where the air is coming from. I am using a 3/4 full gallon jug wired to the firewall for a fuel supply with both the suction and return line in the jug. That is working well. I have 5 psi fuel pressure while cranking that goes up to 6 immediately after cranking is done.
I guess my next move is to bypass the fuel filter and rig a fuel line directly from the lift pump to the injection pump.
Ideas?? Help!!!!!!!
David
Try running the fuel directly to the ip. Maybe it’s a bad new in box part. The air is obviously getting in somewhere and what may help is to start with an “any and every part is suspect part, new or not” attitude. Keep at it you’ll get it and we will all know what happened to introduce air into the system. Good luck Mark
This morning I bypassed the engine fuel filter with clear hoses on the both the supply and return. There were no bubbles in the return during bleeding the pump. Cranking the engine over sent flurries of bubbles out the return line. I bled the injectors but couldn't get it fired up today. At this point I have to think I got a bad new injector that is leaking compression air back past the pop off valve during cranking. Do you have a way to discern the bad injector ? I'm thinking I have to buy one more and swap them out one at a time. Does this sound correct based on the symptoms?? Thanks,
This morning I bypassed the engine fuel filter with clear hoses on the both the supply and return. There were no bubbles in the return during bleeding the pump. Cranking the engine over sent flurries of bubbles out the return line. I bled the injectors but couldn't get it fired up today. At this point I have to think I got a bad new injector that is leaking compression air back past the pop off valve during cranking. Do you have a way to discern the bad injector ? I'm thinking I have to buy one more and swap them out one at a time. Does this sound correct based on the symptoms?? Thanks,
If you have a decent injection shop near you they should be able to pop test them and if you have a bad one I would be getting ahold of the folks that sold you those injectors for some reimbursement
Big news today!!! There are zero bubbles in the return line as of twenty minutes ago.
Going on the theory that each set of injectors had one bad injector I started swapping them around. I put three of the old ones in the first 3 cylinders,,, no change, bubbles still.
Then I put the 3 new ones I'd taken from the forward cylinders in the 3 aft cylinders. and WafreakinHoo!! No bubbles in the return line !!!!!!!!!!!!!11
It's a big day for me,, this rig has been broken 150 yards down the street for almost 3 weeks.
I need to bleed it more and the starter was getting hot so I quit for the day. It sound better already like it's hitting on more cylinders
. I have a question about bleeding,,, how far do you back the nuts off on the injectors,, a turn or two, or more ? I've never seen it mention clearly.
Thanks!
I wouldn't back them off more than 1/4 turn. Then crank until a full spray comes from each one. If you have help you can tighten them down one at a time while it is being cranked. Beware though, the spray is under very high pressure and can cut skin. Wear a good set of leather gloves.
After my last post I started seeing bubbles in the return line again. I took the 6 new and 3 of the old injectors down to Pete's Diesel for testing after I found out he had a tester. He said only one leaked down during the leakdown test and they all popped off at the right pressure.
So,,,,,,,,, I got this idea that maybe I got a bad load of fuel and this happened right after fueling to drive to the North Rim of the Grand Canyon.
I got 2 gallons of fuel from a different station and it was way lighter in color than what was in the camper. I reassembled the engine and did a bleeding. The engine then instantly started with a puff of ether and started acting normally again with no stumbling or missing. It was smoking coming up the hill back home but it was all there and revving well..
Bad fuel was the cause of all this air?? I googled about contaminated fuel causing air in the injection system, but found nothing .
The camper is now home and off the street. I thank everyone who offered ideas and suggestions during this longest breakdown of my life. Whew !!!!!!!!!!!!!
07-02-2021, 11:14 AM
