How do i test if a mechanical bosch lift pump has failed. I can push on the primer attached to the pump and get fuel to flow to the IP, but when I crank, no fuel flows
Year : 1991
Make : Ford
Engine: 6.6L Brazilian/New Holland Turbo
1. Priming with the hand pump on the lift pump, opening up the bleed screw on the fuel filters and then priming a bit more and trying to start
2. When I hand prime, plenty of fuel will eventually come out of the return line and the line going to the IP (maybe after 40ish pumps). When I crank, it doesn't look like any fuel is flowing.
Could I have an air leak somewhere in the low pressure fuel lines and still be able to hand prime?
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Hello, my name is XXXXX XXX I can help you with your question.
Is your lift pump the type mounted on the side of a Bosch in line injection pump?
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I don't want to hold you up when you get back so I am going to open this question back up to other Experts so that we can get you going as quick as possible. If have time to respond an on one helps you by the time I get back I will do my best to help you out.
Hi,sorry if missed you just there. I didn't realize there was a chat-like function.the lift pump is indeed mounted on the side of a inline injection pump
Not a problem. I had to duck out for a few minutes to help my wife.
The style of Bosch lift pump that you have is by far one of the most common. It is a service able lift pump and can be easily tested.
First of all one of the common problems with these pumps is the hand primer. If you notice that the hand primer leaks fuel when pumping then there is a good chance that it sucks air when the mechanical pump is operating preventing good fuel flow. If you remove the suction line from the pump and crank the engine with your finger over the inlet you should quickly feel suction on your finger. If you do not notice suction then there is an internal problem.
The pump has three main components for pumping, the two check valves #4 in the diagram and the main pumping plunger under the #7 cap. When the check valves fail it becomes difficult for the pump to hold suction and often you will experience fuel bleed back issues. If the main pumping plunger fails then it is most often due to it seizing in the bore.
The two check valves can be removed and inspected for wear or damage. If the check valves have circles worn in them or chips (they are ceramic) then they should be replaced.
You can remove the #7 cap and disassemble the pumping plunger. Inspect the plunger and housing for scoring. If you find the pumping plunger seized in place or very scored the whole pump should be replaced.
If this has completely answered your question please hit the green "Accept" button so I get paid for helping you. If you need further assistance simply reply to this message and I will do my best to help you out.
I am a John Deere Ag Tech with over 10 years of expirence.
Hey thanks so much for the info. It turns out the lift pump was indeed functioning and some work i had done was introducing air into the lines. I really appreciate your help even though it turns out it was my own stupidity that was the problem (ive found usually the case). I really like the way this site works--im an independent web programmer and I appreciate independent income, etc. I'm going to accept your answer now. I do have another quick question, and feel free to reply or not, im not sure if the site will let us keep talking after i accept, but my email is:XXX@XXXXXX.XXXthe question is:where would i go/how would i find a lift pump to replace the one i have just in case i need to replace it? I've tried searching for the set of numbers that is on the pump:9 440 080 018but didn't find an exact match anywhere. Do you know where I might find it?
I'm glad to hear that you found the source of the issue. I'm afraid that the site blocks all e-mail address as it only permits conversation within Just Answer.
As far as the fuel transfer pump goes. I would recommend contacting a local injection repair shop as they have access to factory replacement parts.
I'm glad to hear that I could make your first Just Answer experience a positive one.
You are most welcome.