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SE Washington | Got a new to me 8770, having some fuel issues with it. Day after it showed up it wouldn't start, changed both filters and got it primed and going with one guy priming and one cranking. Started fine for a couple days then it wouldn't start again. I'm noticing when I open the bleed screw on the primary round fuel filter it sucks air, is this normal? I had the main fuel line off of that filter housing and fuel seemed to freely flow from the tank.. Also had the primary filter housing apart to make sure it wasn't plugged up with something and seemed fine. Replaced the primer as well because it was leaking, wonder if somebody spent a lot of time priming this thing prior to me getting it. What else should I be checking? |
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SE MN | Before you prime it, you should check to see if there is debris in the water separator filter housing...just unscrew the black plastic cap on top of it and remove the plastic piece under it and make sure that there is nothing stuck in there. That is a place that will catch large things and cause problems and it is very quick and easy to check and clean it. To prime the system, clamp a vise grip on the rubber return line hose coming off of the injector leak off line...at the rear of the engine on right hand side the metal line has a hose clamped to it...pinch off that hose and then pump the hand primer until it builds up with pressure and is hard to push, also make sure the key is on during the hand pumping. After the hand primer pump pumps up it should fire right up. Make sure to remove the vise grip. I believe the problem on them is that the primer pump just keeps on pumping fuel through the return and back to the tank instead of purging the air out of the injection pump. I have been where you are and after I learned this trick from a fellow NAT poster, I now have no problems getting it started. Without this method it could take some time, frustration and a lot of starter wear cranking it over. Good luck and let us know if it starts for you.
Edit: At first I thought your question was about how to prime this tractor, it looks like your question is about the fuel system losing prime after it sits for a while. You might need the check valve replaced which I believe is at the square filter housing. I have also heard of that aluminum housing being cracked and causing the fuel to leak back. I seem to recall that there was a problem in this area with these tractors back when they are almost new and they were replacing a lot of check valves and maybe filter bases as well. For a long time ours would leak back after sitting for a long time in storage, but only if the fuel tanks were 1/2 or less, never if they were full. Don't really know if it does it anymore, doesn't seem to be a problem, but I store it full of fuel too I guess.
Edited by Jd7730 2/24/2015 14:39
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Sandy Hook, MB | Hello Slewis
Did you check the check valve on the fuel filter housing? It prevents the fuel from draining back into the tank. |
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SE Washington | By water separator filter housing do you mean the plastic top of the primary filter? If so I had that entire thing off and apart, it looked fine. I will try clamping the return line. My questions are both about getting it primed as well as it losing prime, driving me crazy. Also where exactly is the check valve, I'm not familiar with it.
Edited by slewis 2/24/2015 14:42
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| +1 on clamping the return hose. You'll likely never get a good prime without doing that. |
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SE Washington | Well I owe you guys a beer. Amazing how quick it went after I clamped it off. Replaced a few o rings in the fuel lines we'll see what happens. Thanks! |
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SE MN | I guess I am assuming that all 8770's have the same fuel filter set-up with a water separator filter and then the primary filter. Also, I have been calling the square one the primary filter, so maybe we are confusing which filter we are talking about. The round one has the water drain at the bottom. On top of this round one there is a plastic cap that screws on and off. I had a bunch of stuff get caught up in the area under this cap and the plug that comes out of there once and the tractor would run great and then randomly loose power and even die sometimes. Cleaned the junk out and problem solved. The square one has the check valve and it is on the bottom right port of the base. It kind of looks like an extra fitting that is between the filter base and supply line. It is part # RE54244. |
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NESD | +1, There is a check valve in the inlet fitting into the filter base, easy to replace once the line is removed. |
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Arkansas | Don't change the fuel filters without full fuel tanks. Much easier to prime with the tanks completely full. Or at least it was on the one I had. |
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SE Washington | So I may be back to square one. Although I was able to get it primed easily enough after clamping the return line shut the first time, it lost prime again after sitting a few days. After that, I replaced 6 of those rubber washers in the fuel lines, the old washers were definitely in rough shape. I also removed the fitting at the bottom right of the square filter housing and it appears that there is no check valve, would somebody have removed it or am I missing something? Opened the bleed plug at the top of the square filter and bled the air out then clamped off the return line, pumped till it wouldn't pump anymore, and attempted to start with a shot of starting fluid. Nothing. Tried this 4 or 5 times till the battery got weak so now it's sitting on the charger. Speaking of which it sure doesn't seem to take long to run the batteries down and I just put 2 new ones on it as well. Also filled the fuel tank all the way before all of this. No debris under the plastic cap on the round filter, so I am running out of ideas other then order a check valve and install it. Also going to try cracking some injector lines at the pump after I get it charged up, but I was under the impression this wasn't necessary but I'm having a terrible time. |
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Deere 8770 fuel priming question
