721D Starting Problems

grumpygator · Apr 7, 2016

First Hello I the new guy here,
A friend brought a 721D over to see if I could get it to run. First thing I noticed was the fuel lines were the wrong size. They were too large for the fittings. so I replaced them and tried to bleed the air out of the system at the bleed screw on the fuel injector pump. This did not seem to work so I isolated the injector pump from the system and ran a gravity feed to the pump inlet. Bled the system at the pump then turned the motor over and bled the injectors one at a time. Then I stopped to refill my temp fuel can and noticed that the fuel level would not sty up in the can.
I checked the glow plugs and they are getting 12 volts but have not removed them yet to bench test them yet.
Is it possible for the injector pump to leak into the crank case?
Any other suggestions would be appreciated.
******Thanks*******Gator*******

bertsmobile1 · Apr 7, 2016

No you can not leak into the crankcase.
However it can leak down the return line .
On electric injectors there is a pressure limiting valve which can fail open so the high pressure fuel just goes strait back to the tank.
On pump timmed motors there is usually not a valve but some sort of mechanical bleed on each injector head.

grumpygator · Apr 7, 2016

Thanks for that I will check the return line.
It's an older model no electrics.
My next move is to take off the tank and clean it then bench check the glow plugs.
After that I will check the compression.
I was told it was running fine when stored for 6 months.
I was using fresh fuel during the bypass so that rules out stale old fuel. The air filter is clean. Any thing I'm forgetting?
I don't work on diesel that often so I could be missing some thing simple .
*******Thanks********Gator********

bertsmobile1 · Apr 8, 2016

The only deisels I play with are on 50 Hp Inters and the 100 Hp Olivers so they ain't exactly new either
AFAIK the high & low pressure sides of the mechanical injecor pumps are not connected.
On one of the pumps we pulled apart ( never going to do that again ) there was a bypass at the high pressure inlet .
This pump was feed by a seperate lift pump and the low pressure by pass is there to protect the lift pump and prevent cavitation.

The pump should have a plate rivited to it's side with the make model series pressure & timing of the pump.
A picture of this would be most helpful.

grumpygator · Apr 8, 2016

Thanks will snap and send one when the sun comes up here.
How's the weather in OZ?
**G**

bertsmobile1 · Apr 8, 2016

We just had a 35 deg C day this week, about 10 Deg above "average"
Been a wet summer for us.
April was a tad warmer than normal which has prolonged the peak mowing season some what and I am still overwhelmed with repairs
Normally at this time I would be calling in mowers for bi-annual services.

grumpygator · Apr 8, 2016

It's been a strange year so far here. This is our spring but we still keep getting the tail end of cold fronts that are pounding the northern states. Last week in the high 80°s F then this week in the low 70°s F with another cold front coming this weekend. Weather fool saying down in the 60°s F during the day and 50°s f at night.
I got some friends in Townsville and another north of Perth. Where are you ?
*G*

bertsmobile1 · Apr 8, 2016

On the outskirts of Sydney.
Offically we are outside the city as the boundry is the Nepaen river which adjoins the lower paddocks.
I live in Springwwod in the lower Blue Mountains.
Workshop is in Silverdale.

grumpygator · Apr 8, 2016

Bert,
Pictures as promised. I know that plastic rod for run/stop is broken but it still works.
I would have logged on earlier but I for got it's Friday. That's when our car club meets. Here is a little eye candy.
****Gator****

bertsmobile1 · Apr 9, 2016

Cars were nice but the pump photo was a liitle blurred

721D Starting Problems

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