2001 70HP Johnson cuts out on low revs

Hi all,
Forum newbie from Australia and hoping someone can help me with an outboard issue. I'm having problems with my 70 HP Johnson cutting out when stopping frequently and running on low revs. Runs no problems on full revs but when drift fishing, we're sitting for periods (15 - 20 mins) and then running on low revs (5 mins) to get back to the fishing spot. After doing this for a half hour or so, when the engine is started and engaged, it dies when trying to apply power above the just engaged setting. Choking seems to get it away which has me thinking it is starving fuel but can't understand why is doesn't die at full revs. Priming does seem to help also. When I do get it back to full revs again, no problems - runs flawlessly. The primer bulb does seem to be retaining fuel. I have read a similar thread to this in the forum but didn't seem to have a solution. If it is fuel related, what could be causing it to starve of fuel on low revs but not at full power?

Cheers
Steve

Re: 2001 70HP Johnson cuts out on low revs

Did you ever try pumping your primer bulb when this prob was happening? You could have a fuel pump prob.

Re: 2001 70HP Johnson cuts out on low revs

Thanks for the feedback Boobie. Went out again today and tried a couple of other things. Took out an external fuel tank to see whether the problem was internal to the motor or in the fuel line or the tank. The problem happened again so at least I can rule out the fuel lines and tank. I tried pumping the fuel bulb but didn't seem to make any difference - the engine continued to die when I tried to apply power. I found, however, that after I started the motor, if I increased the revs in idle for a few seconds, I could hear the engine pick up. Once I applied full power after returning the revs to normal idle, the motor went to full power without a problem. Not sure what this is telling me but looks like it's back to the boat shop tomorrow.

Any ideas appreciated.

Cheers
Steve