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Engine Specific Info and Questions => IDI Engine => Topic started by: vdubspeed on January 02, 2012, 04:39:20 pm

Title: Diesel runs but won't rev up.
Post by: vdubspeed on January 02, 2012, 04:39:20 pm
Fix on page 3!

I bought this little hooligan today for parts but as usual...I tried to get it running AND..of course it still runs...it's a damn diesel! BUT, it doesn't want to rev up. My thinking is that the fuel filter is clogged or the like. The pump is not leaking but apparently the previous owner thought the pump was the problem because there were two more in the car! I have NO history on this car. The battery was from 2006 and was the last bill of sale I found in it.

I wish I had more time tonight to play with it and tomorrow I have to much goin on to mess with it but I plan to pull the feed lines, filter(will replace), and lines to see if they are clogged.

Whatcha think?
http://www.youtube.com/watch?v=E4ExE0HOczo&feature=youtu.be (http://www.youtube.com/watch?v=E4ExE0HOczo&feature=youtu.be)
Title: Re: Diesel runs but won't rev up.
Post by: theman53 on January 02, 2012, 04:50:55 pm
Lift pump could be stuck. Napa or autohaus has Lubri moly diesel purge, run that or atf the old stuff and see if it frees it up. If not it could be the pump. This is of course running it from a can, bypassing the fuel lines and filter. Let it run until the entire can is in the pump...let the feed and return go into the diesel purge can and run it until it is in there. Shut it down and let it sit a day or 7 and try again.
Also, if it is that old I wouldn't run it without checking the timing belt. It could snap any second.
Title: Re: Diesel runs but won't rev up.
Post by: vdubspeed on January 02, 2012, 05:09:22 pm
timing belt looks decent(no cracking)

Not like the diesel I got from the woods that sat 18 years and then STILL ran! The timing belt on that one had been eaten by rats!

I'm actually running this pig on the old fuel. I'll switch to a fresh source with some ATF and see if that clears it up.

Thanks for advice,

Jason
Title: Re: Diesel runs but won't rev up.
Post by: 8v-of-fury on January 02, 2012, 06:10:39 pm
Jason,

You may find that the pump actually is the problem. Here is a scenario that fits why there is two more pumps i nthe car and the owner suspected pumps. Over tightening of the timing belt can cause premature failure of the pumps shaft bushing.. and that will allow air to be sucked in to the suction side of the pump closest to the pulley. He over tightened everyone of them and had to same reoccurring problem. Fits eh. lol

However being that you havent had any time to do some real diagnosing.. its a hard thing to say. But to narrow it down and make the least bit of work out of everything. Id start with;

Title: Re: Diesel runs but won't rev up.
Post by: burn_your_money on January 02, 2012, 06:46:08 pm
Wow that car looks pretty clean. Are you sure it's for parts?

I'm in the clogged filter group. Run it off a jug of diesel and see what happens.

Have you checked the air filter?

The exhaust might be all clogged up too. You could try popping the c-clips off. More of a last resort though...
Title: Re: Diesel runs but won't rev up.
Post by: J Z on January 02, 2012, 06:51:22 pm
Just a thought ..

Maybe the previous owners have been fiddling with the orientation of the throttle lever ?
It sounds like something that could occur after doing the governor Mod, if you can not find the right spline.
Title: Re: Diesel runs but won't rev up.
Post by: 81 vw pu on January 02, 2012, 10:13:43 pm
Quote from: burn_your_money on January 02, 2012, 06:46:08 pm


Have you checked the air filter?

The exhaust might be all clogged up too. You could try popping the c-clips off. More of a last resort though...
^^^^x2 on this as I had the same issue on a 81 I purchased that had been sitting for a few years.
The muffler/exhaust pipe was packed full of walnuts hulls. Would fire up and idle fine but really bog out when you cracked the throttle.
There were a few that came out while trying to rev it,so I knocked a hole in the back of the muffler, fired it up and must have spit 2 gallons of walnuts on the ground.
Title: Re: Diesel runs but won't rev up.
Post by: regcheeseman on January 03, 2012, 03:16:31 am
Before you delve in deep - just check that the correct OUT banjo is fitted to the return line (it is marked with 'OUT')

They can be swapped and it will cause exactly this problem.

The in banjo is free flowing with no restriction, the out banjo has a tiny 1mm hole in it to act as a restriction - fit a normal banjo and it'll idle but not run.
Title: Re: Diesel runs but won't rev up.
Post by: vdubspeed on January 03, 2012, 05:22:43 am
GREAT input guys. I want to add that it has a new air filter on it. I slapped one on yesterday so it has plenty of incoming air.

Hopefully today after I get home I will have a second to look at it. I must say I'm pretty proud of the little guy. Almost cranked this morning and it was 38 outside. Probably would have done it with a warm battery. I will shelf this engine once I get it fired up because it's getting hard to find good running 1.6s anywhere down south.

As for the car itself...it does have potential to be a driver again. I almost hate to kill it BUT I want the parts more than I want to sell it. I could probably only get $500 at BEST for it and I know it's worth WAY more in parts. Also...it's a good 10 footer but the paint job was done at Matco and it's bubbling/rotting all over the place.

More to follow.
Title: Re: Diesel runs but won't rev up.
Post by: Alleslowbuged on January 03, 2012, 06:49:04 am
Hi,

i have had that scenario a few time and the problem was allways the LDA pin, which was ticked on his o-ring.
It that is the reason, don't worry it can be fixed in 15 min.

Remove the LDA cover and than remove the LDA pin and look into the guide rail (of the lda pin) and move the accelarting
lever. When you give "full throttel" you must see a small pin down in the guide rail, which moves out of the casing into the
guide rail. If the pin does that, you have another problem, if the small pin is not moving loose the accelarting lever stop pin
(the long M6 threaded bar), so that you can move the accelarting lever as far as possible. Usually the small pin in the guide
rail will move if the lever is moved at is farest position, than reply that procedure and put some grease on the small pin.

Best Regards and luck
Alleslowbuged   
Title: Re: Diesel runs but won't rev up.
Post by: theman53 on January 03, 2012, 07:16:01 am
N/A pump
Title: Re: Diesel runs but won't rev up.
Post by: vdubspeed on January 03, 2012, 09:20:05 am
does it matter what kinda of ATF I buy? There are so damn many.
Title: Re: Diesel runs but won't rev up.
Post by: R.O.R-2.0 on January 03, 2012, 09:52:19 am
Quote from: vdubspeed on January 03, 2012, 09:20:05 am
does it matter what kinda of ATF I buy? There are so damn many.

the cheapest kind. prolly just some universal dexron..
Title: Re: Diesel runs but won't rev up.
Post by: vdubspeed on January 03, 2012, 01:36:34 pm
Well first off...it did not have the correct banjo bolt. I switched in a good one (OUT) and at the same time made a 50/50 concoction of ATF/fresh diesel. I got the motor running and it still didn't want to rev up. When the pump had sucked in a liter of the mix, I shut it down to let it sit in there. Hopefully something will break free and she will run again.

More to follow...
Title: Re: Diesel runs but won't rev up.
Post by: theman53 on January 03, 2012, 03:50:43 pm
Did it have the correct in bolt? Trying to feed the pump with an out would cause problems too.
Title: Re: Diesel runs but won't rev up.
Post by: fatmobile on January 04, 2012, 10:48:46 pm
Turn in the max fuel screw and see what happens.
Title: Re: Diesel runs but won't rev up.
Post by: 8v-of-fury on January 04, 2012, 10:49:42 pm
i do not think the max fuel screw would hinder the ability to leave idle.. but it is worth a try.
Title: Re: Diesel runs but won't rev up.
Post by: Mark(The Miser)UK on January 05, 2012, 08:46:10 am
Quote from: 8v-of-fury on January 04, 2012, 10:49:42 pm
i do not think the max fuel screw would hinder the ability to leave idle.. but it is worth a try.
Definitely does... whilst experimenting I used the max fuel screw backed off to reduce the revs and got it down to 250rpm ;D However at this point the accelerator won't rev. A good test for fuel injection balance though :o
Title: Re: Diesel runs but won't rev up.
Post by: 8v-of-fury on January 05, 2012, 09:34:32 am
Alright, well he has a normal idle on his car. and it bogs when you go to rev. The accelerator is trying to do something, but something is holding it back.
Title: Re: Diesel runs but won't rev up.
Post by: ORCoaster on January 05, 2012, 10:05:49 am
Does it bog down from too much fuel, a restriction in the line or lack of fuel.  All seem to be classed as bogging down.
Title: Re: Diesel runs but won't rev up.
Post by: Mark(The Miser)UK on January 05, 2012, 02:35:30 pm
If there is too much fuel at the wrong time etc, then it will come out either black, or as white smoke if not contributing to propulsion.
Title: Re: Diesel runs but won't rev up.
Post by: burn_your_money on January 05, 2012, 03:54:05 pm
It could be timed 180 out
Title: Re: Diesel runs but won't rev up.
Post by: vdubspeed on January 06, 2012, 12:49:21 pm
what would have the timing 180 out cause. I think he's played with the pump. The three bolts to the bracket were loose and the on the bottom was missing. The fuel screw was out like 3 turns! I hate when people mess with these things without knowing what they are doing.
Title: Re: Diesel runs but won't rev up.
Post by: theman53 on January 06, 2012, 12:59:00 pm
It is a love hate when people don't know what they are doing. Sometimes it can yeild you a great car for a steal. Sometimes it fights you until it isn't worth it.
I am with you on that one though.
Title: Re: Diesel runs but won't rev up.
Post by: 8v-of-fury on January 06, 2012, 10:09:08 pm
I personally love when people who are unknowing mess with their car and get it so it wont run.. means eeeaassyy pickens for me. I always go and look at the "not currently running" cars around me ;).
Title: Re: Diesel runs but won't rev up.
Post by: vdubspeed on January 07, 2012, 06:34:36 pm
well tonight for laughs and giggles I went out and tried to start it. With one cycle of the glow plugs it fired up like a new car! I attribute that to the ATF/fresh diesel in the pump. However...it never wanted to rev up. I ran it for about 10 minutes and though the idle is ROCK solid...it won't rev up. I don't get any smoke when I rev up either. It has excellent compression so I know that's out. The exhaust is flowing perfect. I put a new air filter on it.

I have a spare pump that I can try but I am going on business and won't be here for a few weeks.

Oh well... at-least it runs. I wasn't even expecting that!
Title: Re: Diesel runs but won't rev up.
Post by: Dieselstink on January 07, 2012, 06:57:14 pm
Sounds just like the accelerator lever is not indexed to the shaft correctly.  Pull the lever, rotate the shaft CCW until you feel spring tension and then let the shaft return gently.  The return spot is usually 1 spline too far for idle.
Title: Re: Diesel runs but won't rev up.
Post by: rallydiesel on January 07, 2012, 08:01:03 pm
Other possibility that I have seen is the governor axis shaft sleeve is seized onto its shaft by corrosion. This is the part of the pump that the spinning governor weights push against to limit the internal throttle lever travel. If this seizes from sitting for long periods, it will prevent the external accelerator arm from increasing fuel but it will still move as if normal.

The governor shaft sleeve I am talking about is the black tube surrounding by the triangular governor weights. The end of it sits against the black accelerator levers and slides on the shaft with the loose nut in this pic.

(http://bricofoy.free.fr/voiture/pompe/dsc05397.jpg)
Title: Re: Diesel runs but won't rev up.
Post by: fatmobile on January 09, 2012, 09:23:23 pm
That shaft freezes, the weights don't come out and it revs REALLY HIGH when you start it.
 I've had this exact thing happen but can't think what caused it, ha.
 Other than the max fuel screw not being screwed in far enough after replacing the top.
Title: Re: Diesel runs but won't rev up.
Post by: R.O.R-2.0 on January 09, 2012, 09:26:50 pm
Quote from: Dieselstink on January 07, 2012, 06:57:14 pm
Sounds just like the accelerator lever is not indexed to the shaft correctly.  Pull the lever, rotate the shaft CCW until you feel spring tension and then let the shaft return gently.  The return spot is usually 1 spline too far for idle.

x2..

had a pump do EXACTLY this before.. rock solid idle, no throttle AT ALL!
Title: Re: Diesel runs but won't rev up.
Post by: ORCoaster on January 10, 2012, 12:06:47 pm
I have a spare pump that does exactly as described.  All or idle, nothing in between.  Some wear on the four little tabs that are spun around by the pump but otherwise couldn't see why I was not fuelling as normal.

Can someone have success in solving this trouble for us?
Title: Re: Diesel runs but won't rev up.
Post by: vdubspeed on January 22, 2012, 04:48:17 pm
Quote from: Dieselstink on January 07, 2012, 06:57:14 pm
Sounds just like the accelerator lever is not indexed to the shaft correctly.  Pull the lever, rotate the shaft CCW until you feel spring tension and then let the shaft return gently.  The return spot is usually 1 spline too far for idle.

WINNER!

I've been gone for two weeks and today I went to start it...instant start. So I pull the accelerator lever and it was WAY off.

So I removed the lever and got it running. When I rotated the shaft I noticed a dead zone and then it TOOK off!!! Yeah...run away diesel!!! After it ran away on me two times I decided to pull the max fuel screw back. I had it set at the factory stop but for all I know it wasn't the factory screw/stop. So after I pulled it back and turned the shaft...I got it running again.

After messing with the fuel screw, accelerator shaft and idle stop, I had it idling and revving perfectly. A quick trip around the block and it ran PERFECT!!! Still pours a cloud of black smoke so I'm sure I could pull the fuel back a little more too. I'm just so damn happy it was such a simple fix.

This car/motor was never bought to drive but damn...I can't see myself ripping it apart just yet since it's an early westy, diesel, has a/c/heat and runs like a scolded dog!

Thanks everyone,

Jason
Title: Re: Diesel runs but won't rev up.
Post by: 8v-of-fury on January 23, 2012, 03:49:30 pm
Jason, do everything in your power to keep this one whole :)

You do good work, this thing is lucky to have happened in to your hands :D.
Title: Re: Diesel runs but won't rev up.
Post by: vdubspeed on January 24, 2012, 03:18:55 pm
Quote from: 8v-of-fury on January 23, 2012, 03:49:30 pm
Jason, do everything in your power to keep this one whole :)

You do good work, this thing is lucky to have happened in to your hands :D.

You will be happy then. This car is getting sold to a local friend who will breathe incredible amounts of life into it. :D