Jump to content

No revs!


swift1894

Featured Posts

Bit of a worry this morning. Cast off in fairly windy conditions and......no revs available!

Went down into the engine room checked/ tweaked all the linkages and suddenly got control of engine revs again. What could have been the cause? Something sticking in the fuel pump etc?

4LW btw.

Link to comment
Share on other sites

Is the Gardner new to you? When I first got ours I found that if I cast off and got going straight after starting it, when I cast off the revs would indeed "plateau" and the engine would not, at first, go much over tickover. I learned to let it warm up for ten minutes before casting off, problem solved.

 

If, of course, you're an experienced Gardner owner you'll know this already, so my apologies if I'm teaching Gardner to suck eggs.

Link to comment
Share on other sites

Bit of a worry this morning. Cast off in fairly windy conditions and......no revs available!

Went down into the engine room checked/ tweaked all the linkages and suddenly got control of engine revs again. What could have been the cause? Something sticking in the fuel pump etc?

4LW btw.

If it was mine ! I would renew air filter & renew Fuel filter, Yes a couple of mins to warm ! ( if not it's SCRAP !!! ) Please leave in MY scrap pile ( I will recycle reponsibly, Honest !! )

Link to comment
Share on other sites

Is the Gardner new to you? When I first got ours I found that if I cast off and got going straight after starting it, when I cast off the revs would indeed "plateau" and the engine would not, at first, go much over tickover. I learned to let it warm up for ten minutes before casting off, problem solved.

 

If, of course, you're an experienced Gardner owner you'll know this already, so my apologies if I'm teaching Gardner to suck eggs.

 

Our 2LW is exactly the same. No go when cold, needs a good warm up, particularly if the domestic battery bank is low and the alternator is working hard.

Link to comment
Share on other sites

the alternator will use more engine power if it has to work hard to charge the battery.

 

If you have a rev counter on your car, look at the rev counter when you switch the lights on, ithe revs may well drop slightly when you flick the switch.

Same goes for air conditionning etc.

Link to comment
Share on other sites

the alternator will use more engine power if it has to work hard to charge the battery.

 

If you have a rev counter on your car, look at the rev counter when you switch the lights on, ithe revs may well drop slightly when you flick the switch.

Same goes for air conditionning etc.

Yes but they would still increase if you put your foot down on the accelerator. I couldn't get any increase in revs even though I pulled the throttle lever back.

Link to comment
Share on other sites

Yes but they would still increase if you put your foot down on the accelerator. I couldn't get any increase in revs even though I pulled the throttle lever back.

No, if you look back to my earlier post, that is what I explained. If the engine is cold, it will not rev up. It will, however, do so in neutral - does yours?

Link to comment
Share on other sites

30 odd years ago I had to deal with a truck with a similar issue (cummins engine) free revving on light load - no power under load, after a lot of head-scratching we replaced all the 'new' factors fuel filters with OEM filters from the dealer. In my next life I had a pal with a class 37 diesel loco not working to power on the test-bank. After much head scratching (almost a day) I was found that the main fuel valve was partially closed, it was opened properly and there was the power.

 

Moral not enough fuel means not enough power. Check filters and fuel cocks.

Edited by Grebe
Link to comment
Share on other sites

I would say check and or replace all of the fuel filters as if no real black smoke there must be a partial fuel starvation which reduces the output significantly until the engine warms up and the alternator load drops. Seems to be even more common with the trend towards larger alternators.

Link to comment
Share on other sites

I would say check and or replace all of the fuel filters as if no real black smoke there must be a partial fuel starvation which reduces the output significantly until the engine warms up and the alternator load drops. Seems to be even more common with the trend towards larger alternators.

I guess as the engine warms up, the fuel gets locally warmed as it comes into the engine bay, and thus its viscosity drops allowing it to get through obstructions like blocked filters more easily.

Link to comment
Share on other sites

It's an old engine with 'old' design features - really it needs a bit of time to warm through and settle before it's happy. I always run my 2LW for several minutes before opening the throttle.

 

Going back to the late 50's early 60's my dad's Vauxhall Victor was a 'Bu....r' if the engine was cold and 'pulling away' was exciting and needed careful use of the manual choke to stop it cutting out when put under load.

 

I am told ladies overcame this problem with careful use of their handbags.

 

So, give it a chance to warm up and settle and things should improve.

 

L.

Link to comment
Share on other sites

I have never seen the type of sluggishness the OP has described on our 3LW, even when started after being left for weeks in the winter and the boat temperature is a few degrees above zero. Taking up the thread of fuel starvation, try priming with the hand lever on the lift pump and see if tghat makes any difference?

Link to comment
Share on other sites

I have never seen the type of sluggishness the OP has described on our 3LW, even when started after being left for weeks in the winter and the boat temperature is a few degrees above zero. Taking up the thread of fuel starvation, try priming with the hand lever on the lift pump and see if tghat makes any difference?

What I will do is rev the engine up in gear, before casting off, next time we cruise, just to make sure all is in order. I always let the engine warm up for five minutes and this is the first time it's happened in 15 years.

 

Was there any black smoke?

No

30 odd years ago I had to deal with a truck with a similar issue (cummins engine) free revving on light load - no power under load, after a lot of head-scratching we replaced all the 'new' factors fuel filters with OEM filters from the dealer. In my next life I had a pal with a class 37 diesel loco not working to power on the test-bank. After much head scratching (almost a day) I was found that the main fuel valve was partially closed, it was opened properly and there was the power.

 

Moral not enough fuel means not enough power. Check filters and fuel cocks.

I would say check and or replace all of the fuel filters as if no real black smoke there must be a partial fuel starvation which reduces the output significantly until the engine warms up and the alternator load drops. Seems to be even more common with the trend towards larger alternators.

Both fuel filters were replaced only 8 months ago, diesel tank has a sump which collects any Water/grunge so fuel starvation seems unlikely. Batteries were low, so alternator (160 amp) would be working hard. Still can't get my head round why hard working alternator could stop engine from revving!?

Link to comment
Share on other sites

Unlike a petrol engine, any true compression ignition engine is capable of producing full power from the moment it's started from cold.

The LW series has a direct injection combustion chamber design and, in good condition, are excellent starters from cold.

Any hesitation in picking up revs, on or off load, cannot have any other cause than fuel starvation.

Fuel starvation can occur from many different causes . . . . partially blocked filters, including the fine gauze screen in the lift pump, weak lift pump caused by dirt or wear in valves, partially blocked or damaged fuel pipes, and 'waxing' of fuel in cold weather. It's just a matter of working your way through the list until you get to the problem, bearing in mind that it could be a combination of more than just one thing.

 

Ps.

If I had been called out to an engine that had suddenly developed this as a new and first time fault, then the first thing I would check would be the rate of delivery from the lift pump with the engine decompressed and being 'motored' on the starter, and not by means of the priming lever, which may give a falsely good impression of the pump's performance.

Edited by Tony Dunkley
Link to comment
Share on other sites

Ps.

If I had been called out to an engine that had suddenly developed this as a new and first time fault, then the first thing I would check would be the rate of delivery from the lift pump with the engine decompressed and being 'motored' on the starter, and not by means of the priming lever, which may give a falsely good impression of the pump's performance.

So, I presume you mean disconnecting the "out" pipe from the lift pump. What flow would you expect to see if pump was OK

Link to comment
Share on other sites

So, I presume you mean disconnecting the "out" pipe from the lift pump. What flow would you expect to see if pump was OK

A good squirt of fuel on each cycle. The lift pump has to be able to deliver more fuel than the maximum possible demand even at low rpm.

 

If there was no black smoke, it's definitely fuel starvation. I suppose it's possible that the fuel control bar/governor had stuck but more likely some sort of blockage. Even though you say the filters were changed fairly recently, if you have some diesel bug it can block things very quickly. I would drop the filters and have a look for any slime / sludge.

Link to comment
Share on other sites

So, I presume you mean disconnecting the "out" pipe from the lift pump. What flow would you expect to see if pump was OK

 

A substantial 'solid' squirt of fuel every two turns of the crankshaft.

Did the fine gauze screen in the lift pump sediment bowl get cleaned when the filters were last changed?

Edited by Tony Dunkley
Link to comment
Share on other sites

A good squirt of fuel on each cycle. The lift pump has to be able to deliver more fuel than the maximum possible demand even at low rpm.

If there was no black smoke, it's definitely fuel starvation. I suppose it's possible that the fuel control bar/governor had stuck but more likely some sort of blockage. Even though you say the filters were changed fairly recently, if you have some diesel bug it can block things very quickly. I would drop the filters and have a look for any slime / sludge.

A substantial 'solid' squirt of fuel every two turns of the crankshaft.

Did the fine gauze screen in the lift pump sediment bowl get cleaned when the filters were last changed?

I will check the filters. I always put Startron treatment every time I fill the diesel tank. Strangely enough I cleaned the sediment bowl in the pump for the first time in 15 years last time I changed the filters ( didn't know there was one till this year)? Fortunately there wasn't much gunge in it. Is there a way of lubricating the fuel control bar? Edited by swift1894
Link to comment
Share on other sites

I will check the filters. I always put Startron treatment every time I fill the diesel tank. Strangely enough I cleaned the sediment bowl in the pump for the first time in 15 years last time I changed the filters ( didn't know there was one till this year)

 

It's not clear from what you say if there is still a fine gauze filter in the sediment bowl. They sometimes get thrown away if they're damaged and then not replaced. If the gauze is missing or damaged then dirt gets into the lift pump valves, prevents them from seating properly, and reduces the pump efficiency/output.

Lift pump valves and springs also wear out/fail due to old age and running hours, reducing the pump efficiency/capacity in the same way as being clogged up with muck does.

Edited by Tony Dunkley
Link to comment
Share on other sites

Still can't get my head round why hard working alternator could stop engine from revving!?

 

When the engine is warming up it is not producing as much power as at typical operating temperature, so when the alternator is working hard, and you do have a large alternator which was working hard, against a low battery bank this puts considerable load on and hence you will have less power available to pull away.

 

That is why the large hard working alternator is relevant as it reduces the power left to rev up the engine in gear. Any loss of power through partial fuel starvation etc will then be amplified. To be honest my view is just warm the engine up for 5-10 mins before you pull away and you probably will not see this again.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.