S195 Moving on from the 'no pump output' problem.

[stevek]

Finally got it to start but still having problems and still working on it being fuel related.
Will start if I set the speed control about half way between 'start' and 'max', runs but shuts down if speed is reduced at all and "backfired" on me several times. That made me nervous, so I'm working toward getting it to start with the speed control set at the start position.

Had the injector hooked up out of the engine and cranked it through by hand. Got a spray of fuel in a cross pattern, each of the four jets of fuel is needle-like for about 6 to 8 inches, then atomizes out another 6 inches or so. I've never heard a distinct click, clink, creak or any such sound from the injector, in or out of the engine. I thought I heard it at one time but think I was hearing what I wanted to be there.
I'm also getting a spray of fuel with every cycle of the pump, so it's spraying twice in a full combustion cycle. I might be showing my ignorance but shouldn't it only inject fuel on one of the four strokes in the cycle?

Also noticed in the bleeding process that compression would push the fuel that was in the injector back out through the inlet port. Thinking there might be some debris in the injector I took the injector apart, cleaned it with alcohol and reassembled.
Marked the position of the pressure adjustment screw and counted turns while removing. Noted that there was little to no tension on the spring that sets the opening pressure.
Put everything back together as is was, hooked it back up outside the engine and cranked it through, still got the fuel injecting on each stroke of the pump. Tried adding tension to the opening pressure adjusting spring one turn at a time until the adjusting screw was almost bottomed out, seemed to make a difference on the amount of fuel coming out of the injector but not in the injecting on each stroke of the pump. Put the adjusting screw back where it was and reinstalled the injector.

Left the return line off the injector and tried starting adding tension to the pressure adjusting spring half a turn at a time. After two full turns on the adjusting screw still wouldn't start so I put everything back where it was initially. Never got any fuel out of the 'return' port. Don't know if that means anything or not.

Tomorrow I'll check and see if compression is still  pushing fuel back through the injector.

I'm going to disassemble the injector again and give it another look. I'll take a couple of pictures and post, the injector I have looks nothing like the exploded view in the manual I have.

Still trying to keep from getting ahead of myself on this, could I still have not bled the fuel system properly?

Any words of wisdom would be welcome.

SteveK

[mobile_bob]

your injector is in need of service
it should pop off and atomize well,

also there should be no compression being forced back up an out the high pressure line fitting as you describe

get it serviced or replaced and all will be fine

btw, the pump is driven at half engine speed, so it injects every other stroke as needed.

bob g

[mobile_bob]

with 4 holes in the injector tip i am thinking you have a direct injected engine?
if so the compression ratio is lower than the indirect injected engine, which is fine but..

if you have an injector that does not pop off properly, but puts out streams of fuel, it will be very hard to start and run like crap.

the fact you are seeing compression coming back up the inlet as you describe it, ends up putting effectively air back into the injection line, which you will never be able to fully bleed out, because every time you crank it over it will push more air into the line. and it will push a lot more when running.

if i were you, i would quit fooling around with the injector and take it to a diesel injection service company, they are set up to service the injector, reset its pop off pressure and test the result.  all of which is tough to do as a diy'er that is unfamiliar in how to do all the above... this is one place that expert help pays off.

for about 37 years i did all sorts of things with diesel engine's of all the popular makes for heavy trucks. engines like cat, cummins, detroit, mack, international and a few others like gm's... we never fooled with the injectors, you either swapped them for reconditioned units or sent them in for cleaning and recalibration.

if we didn't do it professionally in the shops, i see no reason to do it as a diy'er
unless you just have the time and want to learn how to do it?

as an example of what i am relating here,

sometimes things like the injector tip is the cause of the problem with atomization, many well meaning DIY guys will use a wire brush or wire wheel to clean the carbon off the tip as part of their regular service. this really messes up an injectors ability to atomize properly.

those little holes must have sharp edges on the outlet of their passages, wire wheels have a tendency to round off those little holes, the result is the fuel does not break up and atomize as it exits those holes.  this i a hard thing to see unless you know what to look for and have good light and magnification.

good luck
bob g

[stevek]

Thanks Bob, I'll take your advice.
The only info I can take with me is the spec's page from the manual that came with the engine. The exploded view of the injector in the manual looks nothing like the injector I'm dealing with. Will that be enough for the shop to work with?

Luckily I haven't done anything to the injector other than disassemble & reassemble and handled carefully in the process. Wiped the tip of the nozzle with alcohol & a paper towel but nothing more than that.

I've attached a scan of the page from the manual.
The injector pressure is one odd looking spec. Does it make any sense to you?

Thanks Again.
SteveK

[Henry W]

Hi SteveK,

The S195 direct injected engines do not have a glow plug. The injector is long and thin. The dia. of the injector body is roughly 3/8". The injecter has 4 holes. I would also recommend bringing the injector pump to a fuel injection shop. I would also have them do a pop test and leak down on the injector. There could be problems with the nozzel.

Henry

[Henry W]

12748 KPa = 1848 PSI. Be careful with the manuals. Lots of the manuals were not updated for direct injected engines. The compression said 20-1 in my manual but actual compression was 17-1 the S-195 DI engine. It also shows the IDI nozzel. So I knew the manual could not be trusted.

[stevek]

hwew,
About 1850 was what I came up with also. Don't have any idea what the "+980" could mean.

Anyone have a good number for the injector pressure? 1850 psi just doesn't seem right but then again I'm a novice at this.

I think I'm in the same boat on the manual. The one I have shows a much shorter injector nozzle with no flange to pick up the two mounting studs in the head and different internals.
Most of the other stuff looks the same.