Why do I get no revs or flat out?

Canal Boat - - Skin Tanks - WAYNE PRICE, TONY REPLIES…

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?

via email

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...

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.