No power under 2300 rpm 300d

[mikethezipper]

Recently my 84 300d has lost all power under 2300 rpm, it just doesn't really do anything. It wouldn't matter as I have never had too much power under that range, but now, from a dead stop and full ...diesel, it takes over 10 seconds to get up to 2300 ish but when it does I'm fine.

It started doing this about 400 miles ago. About 1800 miles ago (or a week) I re-timed the injection pump and cleared out the crap in the overboost protection valve and wow it ran amazing up until about 400 miles (yesterday). I checked the throttle linkage, and it seems to be fine, giving the ip all it can take. I did notice a slight leak at the ip around the first line due to the re-ttiming I did, but it has been like that since I re-did the timing. Any ideas? Also, it loses power very easily, as iin if I am going 60 and go up a hill pedal to the flo' it ends up at a crawl....

[toomany MBZ]

Sounds like a fuel issue, do you need to clean out those lines and banjo bolts again?

[kerry]

fuel filters?

[TnBob]

Your describing what many here have to find a reeeallly dirty fuel tank that just keeps on giving.

[mikethezipper]

Well I just replaced both fuel filters, cleaned out all alda related lines, and bypassed the tank entirely using a 1 gal jug of diesel hooked up to the hand pump and the cigar hose. Only a very very small incrase in power...but still very far from what she should be. I'm getting desperate going up mild inclines at 4mph the whole way. People are getting angry it. It all happened when I let my girl drive the car any chance the ip loosened itself ? I put. It back in snugly but not too tight either...

[amccoy]

wow,
Started to post this morning-took the girls out to enjoy the day, finished the post (had to relogin) and hit post. Then checked to see if mine was up and found yours.
Sounds like I am having the same problem.

[Diesel911]

Fuel pressure relief valve adjustment/ bypass valve
Fuel pressure relief valve adjustment

I am thinking it is the above or it is a Lift/Fuel Supply Pump issue. Unfortunately it is not easy to connect a Gauge to check your Lift/Fuel Supply Pump Pressure.

If it was a Filter/s Issue alone you would be having trouble going fast.

I would recheck your Throttle Linkage making sure your IP Throttle Arm goes all the way to the limit stop. Watch the Linkages while someone else steps slowly on the Pedal and see how much play is in the Linkage before the IP Throttle Arm starts moving.

Check the Bell Crank on the Fire wall that is between the Pedal Linkage and the Linkage going to the Engine.

[mikethezipper]

I just triple checked the linkage and behold, it isn't going all the way, which I didn't notice because I thought pulling on it by hand would suffice. I don't think that is the problem though as it is almost all the way. That brings up a question I have though.... is the only reason the linkages need to be adjusted to account for wear? It isn't like it is possible to. For them to loosen over time and change length. I had adjusted them as per the MB manual, but I don't think that accounts for the wearing of the balls and sockets. I'll continue reading up on the lift pump and the bypass valve and see what I can do

[toomany MBZ]

Usually, the bushing fails to the point of folks needing to adjust the linkage, then once the real problem is figured out, you have to reset it.
Good luck and keep us posted.

[mikethezipper]

I don't know if I mentioned this, but I am in the middle of a road trip, so doing things like removing the lift pump are... difficult. I checked the bushings and all the throttle linkages and all though they aren't perfect, they are not that bad either. I have a pressure gauge and a tee to tie into the fuel line, but now I have another question... the clear lines from the ip to the filter assy and vice versa and after the lift pump do not seem pliable enough to go over the barbs on the T I have. I would like to replace these lines, but I don't was wondering if I could use any new clear fuel line. I simply ask because the new stuff seems a lot thicker and more pliable. Also, I was wondering that if my lift pump is shot if using an aux fuel pump that I get from napa would at least help out . Thanks again!

[mikethezipper]

I never heard back so I just bought some clear hose from ace, which was rated to the temps in the engine compartment. I put in a fuel pressure gauge between the lift pump and the filter, but the needle bounces all over the place and I can't get a reading..... also, when I pump the primer, there are tons of air bubbles in the line to the filter, but when the car runs there are none... any ideas on how to get a measurement on that pressure?

[mikethezipper]

Just to give this thread an ending, I never figured out WHY any of that happened... All attempts to measure the pressure were a failure (the fuel pressure gauges would either explode, or be unreadable because the fuel pump doesn't supply a constant pressure)....

I pulled the tank out(and pressure washed it clean), replaced all fuel lines, but they were all clean and had no gunk. I am guessing something was stuck somewhere IN the pump in such a way that it wasn't getting pressure, but one day all of a sudden for no good reason, it just started working right again. I wish I could say I know why, but I still don't have a clue

[toomany MBZ]

Cool, better to have unknown solved problem, than a known unsolvable problem.

[charmalu]

Wha type of fuel pressure gauge did you use? you said it exploded.

Charlie

[mikethezipper]

I just bought the fuel pressure gage that O-rielly's had for sale. It didn't seem particularly crappy, but the diesel just kinda went up into the display and then it just popped and sprayed diesel everywhere....