fuel injection problem?

[jschul]

I have a 1970 280 I have been playing with for about 7 years , rusty , wornout , I have cut out and replaced most all rusted parts including the fuel tank ,I sent the injection pump to San Fransisco for a rebuild about 4 or 5 years ago, the engine (short block) and cylinder head was rebuilt by Duffin Engine Service San Antonio several years ago,I put it all together over this long weekend ,got it started but missing on #6 no fuel .I removed the #6 fuel line at the head installed a spare injector,no spray with the engine running, I removed the line at the pump,no fuel,with the engine running.Could the supply pressure be low,would that cause problem? I have looked for imformation on the fuel pressure regulator is this just a spring and dipharam?

[geezer]

It might be a stuck #6 plunger in the injection pump.  You should be able to check if it's moving by removing the #6 delivery valve from the pump.  Sometimes the plunger can be freed by using something like Berryman's Chemtool.   There is a link in the Technical Manual that shows how the pump works.  It's in German but Google has a translation utility that works with the document.

The electric pump needs to deliver about 1 gallon per minute return to the gas tank & pressure to the inj pump should be about 15psi, if memory serves me well.

[ja17]

Hello,

That 19mm fitting on the injection pump must be torqued in at least 18 ft lbs or that cylinder will not squiirt!  Actually the specs for a 280 are even a few pounds higher. Do not overtorque or you can damage the pump.

Normally if a plunger is stuck, the rack in the pump sticks also.

Be aware that the #6 cylinder of the IP is #1 cylinder of the engine.

Yes, view the piston in the IP while cranking the engine to make sure it is going up and down as the engine rotates.  to do this you will need to remove the line, remove the 19mm fitting, remove the ball check valve below and the piston will be visable.

Keep us up to date.

[jschul]

I fiddled with the 280sl again this weekend,drained the fuel tamk,changed the fuel filter,checked the fuel pressure @ start nozzle(10 psi with blocked return),still no fuel on #6 cylinder,swaped #1 & #6 delivery valves,still no fuel on #6 cylinder.I removed the side cover of the pump to look,looks O K  to me,again I removed the delivery valves from #1 & #6 on the injection pump, manually worked the rack rod both moved the same,I used a seal pick and was able to move the #6 injector piston up and down with only slight pressure,#1 would not move at all with the same pressure,rotated the engine several times with the same results,does anyone know a good injection pump rebuilder.

[ja17]

Hello,

It sounds like you have #1 piston  stuck. Number one piston on the IP feeds number six cylinder of the engine.
Try gently tapping down on it with some hard wood or soft metal (alum or brass). Be gentle. If it does not move turn the engine a bit since the cam lobe in the IP could be in the up position. Try tapping it again or repeat turning engine. At some point the piston should begin to move down. Turn engine to bring it back up and repeat. Use penetrant during the process. Exercise until all is free and working properly. No rebuilder required in most cases!