SDL fuel issues..........the trip from hell........ - Page 4 - PeachParts Mercedes-Benz Forum

mplafleur · #46 06-10-2009, 07:17 AM

Quote:

Originally Posted by Brian Carlton

Were you able to see the air in the line from the pump to the secondary?

It's difficult to diagnose air visually due to the very dark lines after 20 years.

Many folks struggle with air...........be good to know how to find it if it's not visible. The Mityvac would do it, but it's not easy to attach to the banjo lines.

Sorry, no. It's not a verified conclusion. The lines were too dark indeed to actually see the air.

Gene Horr · #47 06-10-2009, 09:59 AM

Mr. Carlton you appear to have the source. There was a larger than normal air bubble in the primary filter. Hand priming removed 75% of the bubble but as soon as I stopped you could see the air bubbling in on the outlet (fuel pump) side. I don't recall this happening before.

...................... Edit ..............

'83 300 SD:

After removing and checking lines it looks like the fuel pump itself is leaking.

The FSM says for remove "remove the two bolts" with a picture showing no bolts. Allparts has a supposed picture at but it shows three apparent mounting holes. Which is correct?

How do people remove the output fuel line from the fuel pump? The A/C hose plus proximity to hand primer makes getting a wrench in there tough. I am having to go almost straight down and don't think there is enough freedom of movement to turn it.

Gene Horr · #48 06-10-2009, 12:37 PM

PS - Where can you buy the clear fuel line?

pawoSD · #49 06-10-2009, 02:52 PM

Quote:

Originally Posted by Gene Horr

PS - Where can you buy the clear fuel line?

Phil may be able to get it, else you'd have to go to the dealer.

Gene Horr · #50 06-10-2009, 02:54 PM

It wasn't listed on the web page for Fastlane. I'll try contacting him directly.

Thanks.

tbomachines · #51 06-10-2009, 02:57 PM

Is that stuff any different than normal plastic fuel line? Sorry-I don't have a picture and I'm not home to peek under the hood. If it is normal low-pressure fuel hose you can get that stuff at Napa or Autozone or something, usually its used for weedeaters and stuff but they have bundles of it in varying thicknesses (should be ok on low pressure)

CarlG · #52 06-10-2009, 03:06 PM

I have seen the clear fuel line at hardware stores.

I recently had an almost identical problem to Mr. Carlton on my 240D. It ended up being the primary filter. It was clogged up so badly that it was pulling a strong enough vacuum between the filter and the pump that it sucked in LOTS of air.

Gene Horr · #53 06-10-2009, 04:02 PM

Phil does carry it - but only as a complete assembly. I got a quote for a complete package for all of the lines, fittings and the fuel pump. It was a lump sum and so I am guessing on the price for the lines and fittings. Not too bad for everything - high tens of US$ - but pricey if all I want is line.

I'll give NAPA a call but unless the line is specifically rated for diesel I would avoid it.

PS - there was another thread I came across when researching this issue on replacing the mechanical pump with an electric one. There was mention of a NAPA pump for $40-$50 that would work. If so the local store has never heard of it. They have two pumps that would work but one produces too low pressure (8 psi) and the other far too high (85 psi or something like that).

jt20 · #54 06-14-2009, 05:31 PM

Brian,

What was your final diagnosis?

Brian Carlton · #55 06-25-2009, 08:18 PM

Sorry for the delay.

Finally got the parts and the time.

Replaced:

Fuel pump
Clear line from fuel pump to secondary filter.
Secondary filter.

Took it for a drive at high power levels and no indication of the problem presented itself.

However, there is a continuous stream of bubbles in the new clear line between the pump and the secondary. This seems improper although it doesn't affect the performance.

Can anyone comment on the copper crush washer that is supposedly used with the fuel pump? The pump piston doesn't seem to require a crush washer and the pump itself sits against the IP with a simple gasket.

My only thoughts are that the primary is leaking. It's difficult to seal the fuel lines against the very smooth plastic that is the typical OE filter these days. I'm at the end of the hose clamp travel and I can still pull the filter right out of the hose without too much effort. This cannot be good.

Palangi · #56 06-25-2009, 08:29 PM

Quote:

Originally Posted by Brian Carlton

Sorry for the delay.

Finally got the parts and the time.

Replaced:

Fuel pump
Clear line from fuel pump to secondary filter.
Secondary filter.

Took it for a drive at high power levels and no indication of the problem presented itself.

However, there is a continuous stream of bubbles in the new clear line between the pump and the secondary. This seems improper although it doesn't affect the performance.

Can anyone comment on the copper crush washer that is supposedly used with the fuel pump? The pump piston doesn't seem to require a crush washer and the pump itself sits against the IP with a simple gasket.

My only thoughts are that the primary is leaking. It's difficult to seal the fuel lines against the very smooth plastic that is the typical OE filter these days. I'm at the end of the hose clamp travel and I can still pull the filter right out of the hose without too much effort. This cannot be good.

I don't know from 603's, but on 616 / 617, I find that 5/16 bulk fuel hose slips a bit, and the proper metric fuel hose (7.5mm, I think??) does not slip.

Brian Carlton · #57 06-25-2009, 08:31 PM

Quote:

Originally Posted by Palangi

I don't know from 603's, but on 616 / 617, I find that 5/16 bulk fuel hose slips a bit, and the proper metric fuel hose (7.5mm, I think??) does not slip.

It could be that I've got to replace that hose and both hose clamps to get a good grip on that crappy plastic.