engine losing power on longer highway runs

[pjb155]

hi all,

i have owned my US imported Z for a few trouble free () years, apart from the usual fuel filler neck letting fumes into the cabin and some electrical stuff.

2 weeks ago i came back from france (St Quentin/Cambrai region) into belgium and after enjoying some smaller roads we decided to do the last 75 miles or so on the highway. after about 10 minutes at highway speed (80-90mph), the engine slowly lost power over 10 second timespam and with the pedal to the metal, we got 3k rpm max. In fourth gear that's not enough to keep up with the pace. there was no backfiring or stuttering.

when i lift my foot off the pedal and push it all the way down again i got a few seconds of power, then back to a hesitant 3k maximum. After we stopped for a bit, the problem came back 5-10mins later. we had to stop a second time and re-fixed all hoses, checking a lot of stuff, voltage of the battery (12.6), engine temp was normal and oil pressure good as usual. so no problems found... we had about a 20min run left back to the garage and the problem didn't occur any more.

could this be a fuel pump issue? or carb setup/needles? i have carb rebuild kits and i could fit an electrical fuel pump with plenty of pressure cheaply. However i'm not sure it that would solve anything. Any suggestions would be greatly appreciated!

cheers,

pj

[John Coffey]

Your fuel pump is not keeping up, float levels are too low, fuel filter slightly clogged, or the fuel tank venting system is not working properly.

[madkaw]

...or dirt in the tank being sucked up and clogging your sending unit

[LeonV]

My first check would be fuel filters.

[Captain_Zeros]

Sounds exactly like when my fuel filter in the electric pump near my tank was clogged.

[Reverend]

Time to drain the tank and wash it. At least thats what i would do.

[bartsscooterservice]

Your fuel pump is not keeping up, float levels are too low, fuel filter slightly clogged, or the fuel tank venting system is not working properly.

Yeah, sounds like the bowls are not filled quick enough.

[pjb155]

great, thanks for the feedback. i'll try all of this over the weekend. The test run will be for later since the weather is really really crappy........