Electric fuel pumps on diesel Injection Pumps

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

dadinabarrel

dadinabarrel

10 Year
Joined
Feb 1, 2014
Threads
21
Messages
473
Location
Brisbane
Can anyone fill me in on fitting an electric fuel pump in line feeding my 1HZ 10mm VE injection pump? I've heard that it enhances the IP performance.

The questions are:

  1. What flow demands are we trying to deliver?
  2. What feed pressure are we after?
  3. Are diesel electric pumps different to petrol?
  4. What else do I need to know?
 
dadinabarrel said:
  1. What else do I need to know?
Click to expand...

That if they are working properly the standard feed pump can draw up to 54 litres an hour. You would be making some huge EGTs to use that amount of fuel.
The FSM mentions 900cca per minute maximum ,so I have multiplied that by 60 minutes.

If your pump is returning fuel to the tank,it obviously doesnt need any more fuel pumped into it,unless the regulater valve is out of adjustment.
The only way it could give more performance is if the existing feed pump is starving the injection pump of fuel.
 
Feed pumps can help keep the pump cool, as it exchanges more fuel through the pump at a higher rate. The fuel and pump get quite hot from compression of the fuel and mechanical operation. This is the idea behind most modern add on fuel pump systems(Fass etc.) It also eliminates starvation if your supply pump is cooked. Not really essential on a pump in good shape, but it wont hurt anything. The regulator will bypass excess to the return anyway.
I wouldn't feed it with more than 10-15 psi.
 
yotahed said:
Feed pumps can help keep the pump cool, as it exchanges more fuel through the pump at a higher rate. The fuel and pump get quite hot from compression of the fuel and mechanical operation. This is the idea behind most modern add on fuel pump systems(Fass etc.) It also eliminates starvation if your supply pump is cooked. Not really essential on a pump in good shape, but it wont hurt anything. The regulator will bypass excess to the return anyway.
I wouldn't feed it with more than 10-15 psi.
Click to expand...

Nice to hear this.

It gives more detail to the confirmation I received from two different injection pump rebuild shop techs over the years when I have asked the question about putting a low psi pusher pump in the system for a 1HD-T. Both said yes it is a good idea, and one added "that probably the best thing you can do for the VE pumps longevity". Both said to not hit the backside with too much pressure (10 psi pusher at the tank is a common route).

When a Bosch Rotary VE style pump is rebuilt and bench tested, what is the required pressure supplied to the backside of the pump when specing it out?

Is a pusher pump of some sort OEM supplied on many Bosch Rotary VE injection pumps applications?

Thanks
gb
 
Greg_B said:
Is a pusher pump of some sort OEM supplied on many Bosch Rotary VE injection pumps applications?

Thanks
gb
Click to expand...

The original design brief for the rotary pump was that it be entirely self contained. Ive never heard any injection shop in Australia advocating pusher pumps to increase the life of the pump. As I said in my original post,if the feed pump is working as it should ,the injection will be getting more than adequate volume of fuel to cool and lubricate the injection side of things.
The fuel pump also has a regulator valve so any extra fuel from a pusher pump will be returned to the fuel tank without reaching the plunger or pump head.
You cant pump anymore fuel into a pump that is already full.
 
Last edited:
dadinabarrel said:
Thanks guys, how would I know if it was starving my pump?
Click to expand...

The 1st thing you would notice is it slowing down under full throttle,like when you run out of fuel. A fuel injection shop would be able to run a test but you could run the the fuel return to the tank into a temporary bottle in the engine bay and go for a short drive. If there is fuel returning and no feel of fuel starving,you could assume all is well.
The feed pump is only 250-300mm above the fuel tank,so its not pulling it up a huge hill. The filter is higher but it runs down hill from there.
I've asked the injection shop that I go to and they say its very uncommon for the feed pump to be shagged without the rest of the pump to be worn out.
 
Agreed, this makes no sense. None of the Bosch pumps in the Toyotas, VWs, Audis... have pusher pumps. Not in Norway and not in the Sahara.
The lift pump in the VE pumps are extremely powerful and move a LOT more fuel than they inject. Have you ever ran a stock 1HZ from a jar of diesel? It sucks that thing dry in seconds, and most of the fuel goes back to the tank.
The bypass is before the heat generating parts, so I am not that convinced of the cooling power of the excess fuel either, but I am not 100% sure about that.
In short, if you have a good pump and no air leaks, a pusher pump is for nothing (I think :meh:).
 
It takes the suction tax off the supply pump so it just has to supply positive pressure instead of suction as well. In a smaller application where you are seldom pushing the limits of the supply pump, it isn't such a huge deal, but look at how many VP44 pumps have grenaded from starvation. Yes its a great little design, the VE, as long as you're within OE spec fuelling. Start hotrodding, and you tax the pump more than its designed for.
 
Rotary pumps on Toyotas are a "pressure timed" pump, that means that the timing advance mechanism uses supply fuel pressure in the pump housing to control the advance on the pump (as engine RPM increases so too does the pressure). If you were to add an additional pump that would increase supply pressure at lower RPMs you would begin advancing your timing at lower RPMs which has all sorts of horrible repercussions. If someone from an injection shop has told you it couldn't hurt I'd find a new injection shop.
 
BEE-JAY42 said:
Rotary pumps on Toyotas are a "pressure timed" pump, that means that the timing advance mechanism uses supply fuel pressure in the pump housing to control the advance on the pump (as engine RPM increases so too does the pressure). If you were to add an additional pump that would increase supply pressure at lower RPMs you would begin advancing your timing at lower RPMs which has all sorts of horrible repercussions. If someone from an injection shop has told you it couldn't hurt I'd find a new injection shop.
Click to expand...

What pressure do rebuild shops supply on the backside of these pumps when on the bench being tested?

My understanding is that its around 6 psi supply pressure. Yotahed can confirm or correct what I understand as he's in an injection shop.

This is good conversation, and tech. Better yet would be to have it around a campfire away from it all. Cheers folks.

gb
 
Last edited:
5-6psi in the bench. That wont affect the advance mech.

Like i said, i wouldnt go feeding it with more than 10-15 psi, anything beyond that and your advance would start creeping up sooner. So youre correct Bee-jay42, but only if the pressure is excessive, which I never advocated.
 
I reckon if my pump was worn enough that it needed a pusher to prop up the feed pressure, It'd be time for a new pump. Interesingly, I just found out today that my 10mm VE (from serial number) has an 11mm symetrical fuel pin in it. Has someone has been there before me? Do 10mm pumps come set up like that?

I'm getting some blanks made, so game on from here on in
 
Last edited:
yotahed said:
but look at how many VP44 pumps have grenaded from starvation. .
Click to expand...

This is the problem about the myth of adding pusher pumps. People are extrapolating this problem to all fuel pumps. Ive yet to hear of any rotary pumps dieing from lack of feed pump pressure.
The only thing I have seen that kills the feed pumps in rotary pumps is when you get moisture that settles in the feed pump from lack of use.It causes rust spots that cause pitting on the smooth surfaces and then the feed pump loses pressure.
I think you could also get longer life from an injection pump by keeping the tank as full as possible in hot climates. If you have a small amount of fuel in the tank,recycling it through a hot pump will allow it to keep getting hotter.
Someone in the trade told me he suspected the 1HZ/1HDT pump internals possibly expand from the heat and cause excessive wear ,but that was his opinion and he didnt have any proof.
 
Greg_B said:
What pressure do rebuild shops supply on the backside of these pumps when on the bench being tested?

My understanding is that its around 6 psi supply pressure. Yotahed can confirm or corr


gb
Click to expand...

FSM quotes 2.8psi. Once this has been confirmed,the pump is connected to a drive and the pump is rotated.
At 500 rpm the 1HZ pumps inner pressure should be 36-44psi and at 2000 rpm it should be 101-110psi.
This is controlled by tapping the regulator valve in if its too high or replacing the valve altogether if it is too low.
The overflow volume (1HZ/1PZ)must be 366-800cc a minute.

info is in RM172E ,pages FU76-77

This shows its pointless trying to force more fuel into a pump as you will either over pressurize it or just send higher volumes back to the tank.
Even if you were trying to hotrod your 1HZ,it would need to be consuming a hell of a lot of fuel before it suffered from some kind of starvation.
 
Like i said before, it not nessesary on a VE, and if somebody asked me to install one in a vehicle with a full mechanical VE, I certainly wouldnt do it without altering the injection pump. Both mech. and elec. can benefit from increased supply pressure AND return flow to cool the pump.
You have to balance it out on the mech. as to not screw with the advance.
You can increase the return fitting orifice to allow more return pressure to escape to counter the supply pressure youre feeding into it.
This is why i wouldnt recommend it if you didnt have a higher HP application, or you just wanted to slap one on and call her good to go.
 
I have a small oscillating piston pump - I think that its output pressure is about 3psi, Don't know the flow rate. (It was left over from the old gasser that was installed had a weber carb). I left it in and hooked it up. Been running fine for years.

The big bonus with having it is a much simplified bleed process and if I run out of fuel, it picks up really fast.

It can be noisy, being a piston pump.
 
You must log in or register to reply here.

Share this page

Back
Top Bottom