Why do I get no revs or flat out?
QThe injector pump on my 1999 BMC 1.8 engine was serviced because it leaked on a couple of high pressure banjos. I also changed the spill rail because the original had sheared.
The pump specialists didn’t mention anything untoward other than I needed two new glowplugs; the new ones were as fitted to a Sherpa van. After fitting them, the engine was very difficult to start and, a short while after starting, it began to race at around 3,000rpm. The pump people advised unscrewing the antistall, but this made only a marginal difference.
I have since checked the fuel liftpump for leaks, the oil filler cap and breather pipe for signs of heavy smoke, and bled the pump again to be sure. The pump specialists say they can only assume the engine is running on a mist of sump oil or air intake oil; I fitted another pump and this proved to be no better. Any thoughts?
I am sure the new glowplugs are fine, but check the voltage at the plugs when heating. Also check you have turned the fuel tap back on fully because fuel starvation will make engines with these pumps rev up.
The injector pump (marked 2 in the picture)
Auses an hydraulic governor that can get upset or jam because of water in the fuel, air leaks, or lack of fuel pressure. I would also suggest oil atomisation – usually from overfilling – on a 1.8 that is easily solved by disconnecting the breather hose from the air filter. Check for smells of a gas leak, petrol or thinners fumes, these can get sucked in with the air and give such symptoms.
Loosen the banjo bolt on the top of the filter (marked 1 in the picture) and run the engine with a fuel leak there. If it fails to race, you have found the problem area. Remove the banjo bolt and ensure the 0.5mm side drilling is not blocked.
Are you sure you replaced the two fuel pipes running to/from the injector pump in their correct positions? Getting these the wrong way around might cause your symptoms. The one that has its filter end connected to the non-return valve screwed into the filter body should be connected to the front (timing cover end) of the pump.
Double check for air leaks on the whole supply line and under the liftpump cap for dirt etc. There may be a gauze strainer inside the tank, so try blowing back into the tank. Finally, a long shot: a BMC 1.5 had the same issue and a substitute liftpump solved it, but it came back when the original pump was re-fitted. However, that liftpump worked on another engine. No one can explain that one...