Red run asked questions on electric fuel pump addition;

1. fuel flows from tank to standard mechanical pump mounted on engine,
2. fuel then flows through additional Raycor fuel filer
3. fuel then flows through 5 to 8 lbs electric fuel pump
4. fuel then flows to the standard fuel filter
5. at the top of the standard fuel filter there are 3 outlets.

• the first is to the schrader valve used for bleeding filter
• the second is the line to the injector pump
• the third is a outlet pipe, with a one way air stop flapper valve, and this line send fuel to the fuel return line to the rear tanks
• you can remove the third pipe and plug the pipe with a piece of steel rod and a clamp
• and you also plug the outlet at the filter with a threaded plug insert.

This will remove the chances of air bleeding back into the standard filter vis the flapper valve and allows, with the addition of an electric fuel pump in the lines, to provide very good starting performance provided all other items like starter motor and injector pump and glow plugs and fuel quality are OK.

 

Ah, thanks for the big write up... But I am still wondering why you would block the return line that goes to the filter? Is there a line that returns fuel to the tank meaning there is no use for 2 return lines (one to the filter and one to the tank) or am I not understanding this?

 

the return line your are blocking runs from the filter to the fuel tank at rear of vehicle. This line is to return excess fuel from the filter to the tank and the same fuel return line also takes excess fuel from injector pump to tank.

 

Now I'm really confused.. If you block it, where does all the excess fuel go? Just seems like I would be blocking something I need..

 

The line that comes off of the filter base to the return lines on the nozzles does a few things. One thing is that it keeps from building up to much injection pump housing fuel pressure. It is like a relief line. You can have to much fuel pressure in the housing on the injection pump and it can make them do some silly things. Seen this several times.

It also helps remove the air from the fuel filter when you change it or when the fuel system gets air in it.. Everything, if allowed to, will go the path of least resistance. The air can get out of the fuel system through that line easily and it isn't forced into the injection pump.

You want that line on the motor.

 

Now I'm confused too, I thought it was a good idea to block that line off, to prevent fuel from draining back to the tank with the engine off. What kind of "silly" things have you seen when this line is blocked off? Mine is blocked off since I thought it was a good idea, wondering if I should put it back now .

 

I stumbled across some other posts of yours netmaker, when they were talking about rupturing your mechanical fuel pump and all by having the electric pump between the tank and the mechanical pump.. is that why you posted on here to have the pump between the raycor and the standard filters?.. so it is after the mechanical and there is no rupturing worries?

 

If a truck is having fuel drain backs then there is another problem... That purge line, in my opinion, is pretty important. Like I was saying it will allow air to go to the return fuel system and not have to go through the injection pump. Most trucks will pull air into the fuel system to some degree and most will never have a problem from it. Just changing the fuel filter will get some air into the system and it will leave through that line. I can change my fuel filters on both trucks and they won't skip a beat when I start them. None what so ever. You don't want any air going into the pump if you can help it.

Had a guy bring me a truck awhile back and he was complaining about power and not starting very well. Somebody had told him to block that line and that would help the starting then the truck would start and run for a minute then die. It would start back up but stuble and carry on.. Make a long story short the truck had a bad tank selector valve and it was sucking air and the air would build up in the fuel and when it was shut down the air would rise in the filter and with the line blocked off in had no place to go but in the pump when the truck was started..

I have also seen guys put electric pumps on these motor and the GM diesels that were too big. You can put to much fuel to one of these pumps. It can foam or bubble up in the pump and that isn't good. If a person wants to run alot of fuel through one of these pumps it is a good idea to modify the return valve coming out of the pump. Which I have seen go bad and let fuel drain out of the pump when it is shut down and can cause and hard start.

If a person block that line off and "fixes" a drain back problem they have another issue....