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September 19th - Mis-fire Investigation At the start of the trip to Fishburn Airfield on the
17th, the Jeep was mis-firing and wasn't picking up properly. It seemed to sort
itself out after a couple of miles and the rest of the trip went without
problems. Starting for the return trip took a few goes, but the drive home was
fine too. It still warranted some investigation. |
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I wanted to check all the valves were moving as
they should and also that their gaps were ok. So the first job to access
them was to remove the fender to get better access to the valve cover. Due
to the wiring harness being fastened to the fender, it couldn't be
completely removed, so after all the bolts were removed, it was left
hanging low, balanced on top of the wheel. This was enough to give better
access under the carburettor and manifold.
I didn't want to remove the manifold in case I damaged the gasket, so left it in place and worked under it. It was difficult working around the exhaust, but with virtually no time to order replacement parts, I wanted to disturb as little as possible. All the valves were moving ok, the springs were fine and I checked the gaps. Only the number four cylinder valves had gaps slighly less than I wanted, but they were still within tolerences. With those adjusted, the cover plate edge had Wellseal applied and after a short while to dry, it was refitted to the engine. |
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Before I re-fitted the fender, I was going to give
the engine a short run in case I had an oil leak around the re-fitted
valve cover. I went to prime the carburettor with the fuel pump manual
lever and as I did so, noticed fuel leaking from the inlet pipe into the
carb.
Had the engine been leaking fuel and sucking air in through this joint, messing up the mixture and hence causing the rough running? The joint was dismantled, cleaned and then the copper washer was smoothed off with some fine wet and dry to clean up both of the mating faces. It was then reassembled and the bolt nipped up. Another prime test showed no signs of leaking so I went for an engine start. The engine started ok and was idling smoothly. A few blips of the throttle showed the engine picking up ok from idle and higher RPM checks also showed the engine running smoothly. It was time to take the test to the next step - under load. |
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I grabbed a coat and my daughter and we went out for a test drive, to put some load on the engine and check it operating under normal driving conditions. We left the village and took one of the back lanes until I came across the first parking place; then pulled in. There were no sign of any fuel leaks, but I also wanted to make sure there was no oil leaking from the valve cover. Everything seemed well and the engine was running well. We carried on a couple of miles further and pulled in again for another check. Once again, all was well, so after a couple of pictures, headed back home after a 5 mile round trip. |
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