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Old 05-18-2011, 01:29 PM
Join Date: Jul 2009
Location: B.C. Canada eh!
Posts: 19
1991 350SD hard starting ,lift pump?

Looking for conformation I am on the right track??
Hard starting this past winter West Coast Canada (BC) replaced the glow plugs as I had no idea how old , plus I got a good deal (check) removed and cleaned the fuel tank ,fliter screen and inline filter, screw filter on was done recently, replaced the o ring and crush washers in the IP (check) new battery group 49 (check) still hard to start , Lift pump ??? I have tried to look and see if there was a test? car has 449,000 Km runs fine once started lots of power so have to crank the thing like crazy for it to catch ? is it running only on Injection pump once running ? is that possible with a weak lift pump if indeed that is the cause? I am not looking for more work? Plus if it is the pump rebuild the entire thing or just the o rings?
Thanks in advance!! ;-)

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Old 05-18-2011, 03:22 PM
Registered User
Join Date: Nov 2004
Location: Nova Scotia, Canada.
Posts: 6,510
Changing the glow plugs does not gaurantee they are working. You have to check them for operational condition. You could have an issue with your glow plug relay for example. Meter the voltage to the plugs when the dash light is on pre start to make sure it is there.

Siince you seem to feel it is fuel supply related. Check to see if the relief valve return line from the injection pump is flowing when cranking. You also could have a simple air leak giving you hard starting as well. These are the simple thing to properly check out first.

Since the car runs well once started this kind of eliminates the lift pump other than perhaps fuel back draining through the check valves. If this is the case I feel you should be seeing air bubbles in the return line when cranking. This would also occur with a system air leak as well.

When all is said and done the glow plug function should be verified properly before looking elsewhere.
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Old 05-18-2011, 04:53 PM
Diesel911's Avatar
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Join Date: Sep 2007
Location: Long Beach,CA
Posts: 44,551
The Glow Plug work better and last longer if the Carbon is reamed or otherwise cleaned out of the holes. Spoken of in the DIY Section.

"I am not looking for more work?" I do not see how work can be avoided.

With the Fuel Supply/Lift Pump you could test it (you would have to make your on connections for the Gauge/s); Rebuild it and hope that works or buy another Fuel Supply/Lift Pump and hope that works.
The easiest way is the more expensive and less sure way to trouble shoot; buy an new Lift Pump.

I believe your Pump is similar to the ones below.
Newer Lift Pump Repair with Disc Valves
95 E300D (606.910) Fuel Lift Pump Rebuild Question
606 Fuel/Lift Pump Rebuild
OM606 Fuel Pump Rebuild
84 300D, 82 Volvo 244Gl Diesel
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Old 05-21-2011, 12:49 AM
Join Date: Jul 2009
Location: B.C. Canada eh!
Posts: 19
Thanks for the tips , Sorry work has been hectic.
Ok Glow plugs checked them after I pulled each one hooked it up to 12 vold supply 2 were dead , I replaced them all
Was not getting good fuel supply to inline filter when it was near empty so figured the screen and or tank was dirty. Pulled tank and filter and cleaned it all, Nice flow to filter now.
Changed the rubber oring and crush washers on the IP as I has bubbling on the front line I could see , replaced that one and found others leaked also so changed them all.
I still have the crush washers to do on the injectors next days off

But I still have the starting problem, I wired in a small pump right at the inline fuel filter, wired it into the headlites , turn on parking lites for 5- 10 secs and flashes right up,
You mention the return check valve?? where is that ? After the injection pump returning back to the tank? this would kind of make sence as if I use the pump it starts?
Thanks for the tip will keep you updated
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Old 05-21-2011, 01:18 AM
Join Date: Jul 2009
Location: B.C. Canada eh!
Posts: 19
Sorry spoke to soon last night I looked all over couldn't find the location of the valve, today I find the location right away! I will pull it and clean it and see .
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Old 05-21-2011, 02:22 AM
Diesel911's Avatar
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Join Date: Sep 2007
Location: Long Beach,CA
Posts: 44,551
I do not believe there is a Check Valve in the Fuel Retrun but you can see in the Lift Pump Rebuild threads there is 2 Valves inside of the Lift Pump. One of both of those Valve should keep the Fuel from going back to the Fuel Tank when the Car sits overnight.

There is a Fuel Pressure/Overflow Valve that is right before the Fuel exits the Fuel Injection Pump Housing. I believe on your model there is a small vent hole in the system that is supposed to allow for Air to bleed out of the Fuel Injection Pump Housing (this is one of the reasons there is no Hand Primer In the system). But, since there is a vent there I do not see how it would be responsible for holding the Fuel inside of the Fuel Injection Pump Housing to keep it from going back to the Fuel Tank.
Speaking of the same Valve I suppose it is possible (like in the 617s) for the Spring inside of the Pressure Relief/Over Flow Valve to have issues and not hold enough pressure during starting. And, sometime within that last week or 2 someone posted a pice of the guts of one of the Valve (don't remember the year but it was not s 617) and it had some plastic piece that was all buggered up.
I do not know if yours is the same or not.
84 300D, 82 Volvo 244Gl Diesel
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Old 05-21-2011, 01:20 PM
sixto's Avatar
smoke gets in your eyes
Join Date: Jun 2000
Location: Eastern TN
Posts: 20,833
Is the shutoff lever on the IP fully vertical while glowing? Does it bob while cranking?

87 300D
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Old 05-22-2011, 11:51 PM
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Join Date: Mar 2005
Location: Kennett Square, PA
Posts: 344
I had a problem where the o-ring in the plastic insert in the diesel fuel thermostat was leaking fuel. When the car sat for a while the fuel would drain from the injection pump out the leaky o-ring. This caused injection pump to be starved for fuel on start. The engine would start, but sputter as the injection pump filled up.

If this is happening you will see diesel fuel in the indentation on top of the drivers side engine mount.

The o-ring is a few dollars, but you will want to get the plastic cover for the fuel thermostat, which is a few more dollars.

1991 350SD (updated rods)
Biodiesel B100 when I can find it.
Dino when really cold outside
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