bunny hop

[baron_matt]

On a run in the 126 today a new and worrying thing happened.

At 55mph on a duel carriageway climbing a gentle hill the car started jerking as if it was running out of fuel.
I dropped speed down to 45mph and changed down to 3rd and continued slowly up the hill. Back on the flat  all seemed well.

I noticed that the fuel gauge was reading low so assumed it was lower than indicated and running out of fuel. So at the next fuel station I brimmed it and continued on my way.

At the next hill climbing in 2nd gear it started to do exactly the same thing again.

I'm thinking this is likely to be a fuel issue. If anyone has experienced something like this before can they make any suggestions?

[Gadge]

Seems like it's doing it under load when it demands fuel so maybe a duff fuel pump or perhaps a blockage in the pipe line - most notably near the carb end. There is a little tiny filter gauze in the carb which may well have clogged up. Where the fuel pipe goes into the carb you'll see a big (13mm I think?) nut. If you remove that its in there, just draw it out slowly. If loads of fuel spurts out then the pump is ok as it's under pressure

[baron_matt]

Yep I'll take a look at that this weekend when I'm servicing it.

Hopefully its not the tank.

[andyzeetec]

Firstly check the inline fuel filter isnt blocked also the filter in the carb.

I reading somewhere on here the same sort of problem and it ended up being the filter bag made out of gauze on the fuel sender in the tank, runs fine to start with, but once moving up and down hills, it start sucking up rust floating around in the tank and starves the carb of fuel. (Last resort though, taking the tank off)

[baron_matt]

I take it that if it is the gauze filter in the tank then the only way forward is to drop the tank and either replace it or flush it out?

[thepuddlejumper]

I had a similar problem which turned out to be a worn piston rod, the one that drives the fuel pump.
Ralph

[baron_matt]

I have a nasty feeling that the new fuel pump I have ordered won't fit as I didn't realise there were two types of pump, alternator and dynamo. I have a flat rather than canted base to this new pump.

It has started doing this bunny hop again this morning on a gentle 30mph run on level ground. I have a clear in line filter prior to pump and this seems to show fuel happily moving through the pipe. I'm therefore going to start at the carb end, check for blocked jets, clean out the carb bowl, gauze filter, and check the pump operation.

I think I'll be popping over to see Rusty this weekend for his sage advice.

[baron_matt]

Another busy afternoon on the 126 and I think I have found the cause of the running issues.

First check was the points gap and I found this to be miles wide, I reset this to 0.5mm.

Then when stripping off the air inlet pipework into the carb I discovered that the carb was loose on the manifold. It seems that the studs were vibrating loose, so I removed the carb completely and wound the studs back in with a spot of threadlock.

In the spares I got with the car was a carb sevice kit with all the gaskets and also needle jet, main jet and float pivot.

Stripping the carb down I found a lot of crud in the float bowl, and the gauze filter blocked up with what appears to be aluminium corrosion, from the carb. All this was cleaned out as was the bowl and idle, air correction and other passageways.

The new main jet was fitted as was the float pivot (the float was sticking on the old one), and needle jet. Float height and travel were checked and adjusted as per the haynes. The the carb reassembled with the new gaskets fitted.

As I had the rocker box off I checked the tappets and found them all to be tight. I've adjusted them all to 0.25, I might even go to 0.3 on the exhaust valves after I've run it for a bit.

I've also had a play with the timing and adjusted the hesitancy and hopefully the pinking out too.

Idle speed is about 800rpm which I think is fast but still not quick enough to stop the charging warning light to go out. Finally I replaced the dirty in line fuel filter.

On the short test run it seems much happier, so tomorrow I'll stick some engine flush through it before giving it an oil change. Hopefully it will start better now.

[Pete126]

Tomorrow I'll stick some engine flush through it before giving it an oil change. Hopefully it will start better now.

Hi Matt,

Clean the filter out first before you put the engine flush in, if you don't the crud/dirt in the centrifugal  filter may be circulate through the engine/bearings again

[baron_matt]

Hi Pete

Too late lol

Ok so today was another busy day on the car, oil change and filter cleaned any oh my what a lot of crap came out of the engine. The filter was totally clogged up with crud, and soaking the lid in thinners, then petrol did little to shift it. In the end I had to use a screwdriver to break it up and then blast it out with a can of carb cleaner.

I learned today how to get the rear beam off and had some fun with the engine mount, but I'm pleased to say all is now well.....for the moment. The one thing I did discover is that the alternator bearings are pretty noisy so I better factor in an alternator change pretty soon.

The other job which I managed to cross off the list was the handbrake. This has now been adjusted and actually works.

So with the alternator needing replacement, what is the best way to do this? Keep the engine in or pull it out and sort it? With the engine out I could replace the busted heater hose and maybe fit a recon starter motor at the same time. It works but it is stiff in operation and looks about as good as the alternator.

With the MOT rapidly approaching, I guess the front kingpin is the priority, but I've got to get that alternator replaced soon.

It is certainly keeping me busy this car, but it seems to be liking the new 15/40 oil