Haflinger lacks power

[heinkeljb]

As all of you know, I have been working on my Haflinger for the past 6 months or so. mostly on hte front hubs which turned into a real marathon.

Prior to my first attempt at an MOT, I had a few issues with the engine not starting and running and traced that to an HT lead going to the right hand spark plug as you look at hte engine from the back of the Haflinger. The HT cable had been eaten by some rodent down to the core!
Anyway, the drive to the MOT station and back was fine as far as the engine and power were concerned.

Now I actually have an MOT and can legally drive it on the roads here I am finding that it revs well in Neutral - it is responsive to the accelerator pedal, BUT when I try and drive it....... It bogs down even in 2nd after you have gone a few meters, if you pump the accelerator pedal in an effort to keep the engine running it will pick up again and drive nicely, but the moment you try to change gear it bogs down again. If you are lucky, you can get it to pick up again and appear to have enough power to drive in 3rd, but it definitely does not like it!

Obviously I have my own theories and possible remedies but I thought I would throw it open to all you guys to see if I am going to cover all the bases.

Just in case the first thought as fuel, it had run down to less than an 8th on the fuel gauge and I have put a couple of gallons of 98 octane in. There is also a fuel filter which might be clogged but it is dark by the time I get back in an evening and it is difficult to tell just using a torch.

So lets have your tips for diagnosing and correcting this issue please.

John

[Julian B]

I'm not technically savvy enough to answer your question directly, but what is the rolling resistance of your Haflinger like? How much power is being sapped just to get it to move?

I suffered from bouts of low power a couple of years ago, and that was tracked down to a tiny pin hole in the (Weber) carb float, which prevented the carb from enabling the correct amount of fuel to get into the cylinders. But that doesn't sound like your issue here.

[heinkeljb]

When I took it for the MOT, it didn't feel right, seemed very sluggish. It then died just as I was about to drive it on to the ramp. As we were talking about it I tried starting it and nothing! It failed to turn the engine over, all we got was the solenoid clicking.

So we pushed it back out so we could connect up some jump leads and although it stopped quickly when we stopped pushing. It did not seem to require as much effort to move it as I had expected. So I don't think it is down to rolling resistance. Also when I got back home, I felt all four wheel brake drums. None were even warm, which is not surprising as I think I was travelling at 15 mph most of the way home! If one of the brake drums had been binding then it should have been warm / hot.

Any one else with any ideas?

Hopefully this thread will turn into a sort of step by step fix it!

John

[jhon]

Hi John - like you I've being working hard to get my vehicle running right; I had experienced similar issues but have since managed to get the engine ticking over and revving cleanly under load. It's not perfect, but acceptable. Here's what I did..
Ignition timing - correct points gap and timing 2mm BTDC. Use a timing light to make sure that the timing advances as you increase the revs from tickover. (if the timing doesn't advance it will rev, but you will have no power)
Fuelling - the carburettor jets seems to be really sensitive to dirt - it's worth removing the square plate on the side of the carb, removing the 4 jets and blowing them through with compressed air. This really improved the low speed pick-up and got rid off the spluttering and misfiring. Make sure that your fuel filter is clean and there is no possibility of it passing any fine particles, I fitted a new in-line paper filter and blew through the lines to make sure. Also check your fuel pick-up in the tank and all connections to make sure that there is no blockage or that it is not drawing air.
Disconnect the fuel hose from the carb and turn the engine over - check that the fuel pump is delivering fuel.
Valve clearances per spec.
Air filter clean.
Plugs good and gapped correctly.

If all the above checks out OK you could try a compression test, I don't know the specs* but you should feel it in each cylinder turning the engine over by hand, using the dynostart pulley. Worth checking with a proper gauge if you can access one.

I hope that helps, it sounds like fuelling from what you've written.

(*Edited to add: 1:7.8 equivalent to 115psi)

[ogdenenterprise]

My haf would not run ok when I got it , I found the dip pipe in the fuel tank was blocked , I used plastic waste pipe priming fluid (used to clean the pipe before gluing) was the only thing that would soften the blockage, then I used s/s braided wire to pass through the pipe to clear it, after that it would tick over ok but not rev hard ,I had the carb checked twice professionally,( they said it was ok ) I eventually traced the fault to the adjustable link on the plunger was not set correct.
Dave

[heinkeljb]

I have cleaned the spark plug just because I know they will have been sooted up whilst it was running badly on one cylinder.

The fuel filter has some fine grot in it, so as it is one of these plastic disposable one with the outlet at right angles to the inlet, I have put is at an angle so the grot has fallen down as far away from the outlet as possible. Then I went for a drive and after hiccuping for a while it settled down. Taken it for a 6 / 7 mile drive and other than an occasional cough and splutter, mainly whilst changing gear it seemed to behave it self.

Unfortunately, I am off to South Africa for a couple of weeks from Saturday so I won't be able to do any more fine tuning to it until I get back. No doubt I will have to go through all this again then!

I shall buy one of the Glass bowl fuel filters which are available as that will make the task of getting rid of the rubbish coming from the tank a bit easier. (I know, clean and seal the tank...) Later, I want to drive it first!

John

[HaffyHunter]

Hi John,
The symptoms you've described are that of a lean fuel condition. The engine requires more fuel than it is getting. This may be caused by several factors such as:
1) Air leaks at fuel lines and fittings, intake manifold and carburetor gaskets or worn throttle shafts.
2) Floats set too low
3) Incorrect accelerator pump adjustment
4) Incorrect fuel mixture screw adjustment
5) Dirt in the main and/or idle jets
6) Dirt in the carb passages
7) Dirt in the metering needle valve
8) Dirty/stuck accelerator pump pressure valve
Is the problem alleviated by applying a bit of choke?
Cheers,
Steve

[heinkeljb]

Hi Steve,

I will have the Carb off when i get back and check on all the things you have put in your post. Still have to pack so no time now to do anything.

Later.

John

[heinkeljb]

I have cleaned the Carb and although it runs better now than it did. I still don't think it is right. I get an indicated 42mph, (GPS says 39mph) on a reasonably flat dual carriageway. I just does not want to go any faster, there is still some pedal movement left but using that does not result in any change in speed except possibly a 1mph reduction!

There also seems to be a rather big jump in the gears between 4th and 5th. "Lurch" (as the Hafi has been christened) seems to run out of steam in 4th and so you change gear to 5th and then there is a it of a struggle to get the revs back again. Gear change time between 4th and 5th is as short as possible as it is just straight back on the gear lever, so it can't be losing too much momentum during that gear change.

[HaffyHunter]

Hi John,
Which carb model is fitted to your Haf? The Zenith can be a real stinker to get tuned just right.
What is the condition of the carb base gaskets?
It sounds like your cleaning has helped some but there may be other issues. Then again, maybe not. What hub gear set is in your truck? You may have the lower gear ratio and 42mph is the top end.
Yes, there is a big jump from 4th to 5th gear in the Haf. As 5th gear is overdrive don't expect too much in the way of acceleration. Also, the engine produces maximum torque at approximately 3500rpm so pushing the accelerator pedal further at the high end of the rev range will have diminishing results.
Also, how are the cylinder compression values? Low or unbalanced compression robs power and may indicated things such as improper valve seating or tappet adjustment, worn compression rings, or flared cylinder bores.
Cheers,
Steve

[heinkeljb]

Twin barrel monstrosity! There is a hole in the inlet manifold but as far as I can tell it is on the Carb pre heat tube. I have stuck a piece of metal and exhaust paste with a Jubilee clip as a bandage over it. Probably not completely sealed but the hole will much smaller than before.

Will do a compression test this weekend if I get a chance.

Actually, having had both front hubs apart to rebuild, I didn't bother to look what the numbers were on the cogs! I read in one of the other posts that it might have a number stamped on the wheel flange. I can't see that the hub gears would have been changed unless some one has only changed one hub!

What would happen if you do that? i.e. 3 high speed hub gears and 1 lower speed hub gear set - Broken bits I would suppose?

I guess it is "pull the carb apart again" time this week end when i get back from driving up to see Julian and his brood of Hafi's....

John

[AustHaflinger]

I guess it is "pull the carb apart again" time this week end when i get back from driving up to see Julian and his brood of Hafi's....

John

You going to drive the Haffie

[Rob]

Don't forget the feeble fuel pump.

Cheers,

Rob

[heinkeljb]

Gary,

Of course I am going to drive it! That's why I bought it after all... Should be a round trip of ~ 30 odd miles.

Going up to see Julian and his collection of vehicles which includes 3 Haflingers. Will take my strobe / tachometer unit which will help decide if his newly purchased Tachometer is accurate or not.

It will of course highlight any issues with mine as they are bound to show up on such a journey so there will also be a toolkit, jack and axle stands going along for the drive.

Actually, travelling at 30 / 35 mph average gives you a good opportunity to look at the countryside you are driving through and I have spent many hours at this speed in my Heinkel (bubble car) 150 3 wheeler whilst I drove various places including Germany and Holland in it with a friend and my son until he was about 8 years old.

John

[heinkeljb]

I personally don't think there is anything wrong with my mechanical fuel pump and don't believe the statements I have seen that the mechanical pump uses 2 ~ 3 or even 4 BHP to run thereby depriving the Haflinger of a measurable amount of it meagre BHP output.

All I have read about the debate regarding mechanical / electric fuel pumps highlights possible issues when running 600 BHP and above engines. Supplying fuel to at best a 30BHP engine where a mechanical fuel pump supplies increasing pressure of fuel as engine revs rise means it matches the engines requirements for fuel very nicely. Also any energy required to compress the spring in the mechanical fuel pump is given back almost 100% where in an electric fuel pump you have an almost constant electrical requirement and you don't get any of the energy back from supplying the fuel to the Carb.

Obviously, if you have any sort of issue with your mechanical pump like bad cam face / shape, hole in diaphragm then it is probably a good idea to replace it with an electrical one.

The other reason I see written for changing the mechanic pump for an electric one is priming of the carb on first start - no reason for your carb to require "priming" except if it is empty. If there is fuel in the system then there is no reason for "priming" so a mechanical pump will provide fuel when it is needed. If you fuel system loses pressure then you have a leak which should be fixed - do't blame the mechanical fuel pump for some thing that is not it's fault!

John

[Rob]

I was not trying to offend you.

I was not referring to power absorption by the pump.

These are very low back-pressure pumps that can barely push enough fuel into the float bowl to start even after fitting a new diaphram.

If the pump is leaking backwards excessively then putting your foot down while lugging/accelerating will cause the float level to drop and the carb to lean up.

Cheers,

Rob

[HaffyHunter]

Hi John,
I couldn't agree with you more in regard to the Weber mechanical fuel pump. I've encountered many more problems with electric pumps on off-road vehicles than with original mechanical designs. Besides, rebuild kits for the Haffy's pump are quite reasonably priced and much easier to install than an electric unit. A previous owner of my Haf had installed an electric pump and it was the very first thing that I removed and smashed with a big hammer after getting the truck home. The noise alone of the running pump was enough to drive me nuts.
Cheers,
Steve

[heinkeljb]

Rob,

No offence taken, emotion does not come across the written word the same way as tone of voice does.

Actually, I understand what you are saying. If the one way valve in the pump is not sealing properly then you will get low output.

I might just buy a fuel pump repair kit for the sake of it, because if I open the pump up to check on the state of the internals. It is likely I will break / bend / disturb something which then makes it worse!

Without having even looked at mine except from the outside, I would say it is a very short stroke pump and therefore relies on the one way valve to stop fuel returning to the wrong side of the pump and if the valve is good I am sure it could pump fuel up a vertical pipe several metres. Remember this was originally designed as a military vehicle and so would not have been fitted with a such a marginal fuel pump that it only "just" can fill the float chambers.

Even the electrical system has some extra capacity over and above the electrical requirements of all the electrical consumers (lights, wipers, engine, horn).

John

[AustHaflinger]

Gary,

Of course I am going to drive it! That's why I bought it after all... Should be a round trip of ~ 30 odd miles.

John

The engine will barely get warm over that short distance

Garry

[heinkeljb]

I know, but you have to start with shorter distances in case it breaks down! Less distance to walk home to arrange fix / collection....

Still have to have ago at sorting the gear position as it is a bit hit or miss as to whether you get the next gear or some sort of neutral at the moment. I will also have to make more of an effort to get a set of 13 or 14 inch wheels for road use, the original 12 inch ones are obviously good for off road but are a bit noisy on Tarmac.

John