Power loss

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Power loss

Postby Mike Attew » Thu Jun 28, 2018 12:33 pm

Back on the road so tried the car out today, 1256 now with a Stromberg which I have rebuilt.

First couple of miles all ok, acceleration and power all smooth. I came to a 30 limit and as I was driving through the village it lost power, I had to keep putting my foot down further to keep it picking up. Out of the 30 I went through the gears and it accelerated again ok but cruising at 50 there was a slight power loss again down to 40 so I had to put my foot down again. It idles ok and doesn't cut out which I was afraid of.

I think it's fuel so any experience of this, pump, line from tank which I am going to replace, filter in the tank? can this be cleaned?
I do have an inline filter before the pump which didn't seem to have much fuel in and there seem to have been air bubbling through so maybe and air leak?
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Re: Power loss

Postby droopsnoot » Thu Jun 28, 2018 6:34 pm

When I fitted the inline filter to my Sportshatch, I was surprised that there wasn't much fuel in it while running. Once I'd been through and replaced all the fuel line clips with decent ones that tightened down properly, it's now almost full when the engine is running. So I'd check that you're not drawing air into the fuel line somewhere between the tank and pump input side.
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Re: Power loss

Postby Mike Attew » Thu Jun 28, 2018 9:45 pm

I think I will do that, I am going to change the feed pipe tomorrow so will also renew the flexi pipes, clips and filter.
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Re: Power loss

Postby jpsmit » Fri Jun 29, 2018 3:28 pm

Mike Attew wrote:I think I will do that, I am going to change the feed pipe tomorrow so will also renew the flexi pipes, clips and filter.


However, don't get too fussed if the filter isn't full. My MG runs only about 3-4 lbs of fuels pressure - this is not enough to fill a filter completely. In fact it needs many times that pressure.
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Re: Power loss

Postby Mike Attew » Fri Jun 29, 2018 6:29 pm

I replaced the fuel line from tank to pump today, fuel filter before the pump. So much fun with nearly a full tank. The old pipe was in a pretty rough state. Went for a drive and worse than ever, checked the mixture and it was a bit on the weak side so adjusted richer. Still No response so I put it into 2nd and floored the throttle a couple of times and it ran fine after this apart from one more slight loss of power, floored it again and it all cleared. Reckon it needs running now but don't know what it could have been as all the parts in the Stromberg were new?
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Re: Power loss

Postby Mike Attew » Thu Jul 05, 2018 3:32 pm

This is bugging me now, drove 7 miles to my mothers, part of it at 60mph no problem, driving back 5 miles all ok, then went into a 40 and the car lost speed like braking or fuel starvation. Tried accelerating in top and it wouldn't accelerate so dropped to 3rd and it cleared again?

It has new pipe from tank, flexi pipes, pump, carb needle valve, jet, metering needle, diaphragm, spring. The engine temp was showing about 3/4 across on the gauge but it was hot outside.

Could it be the carb temperature compensator?
I will try changing the coil and plugs next. It has electronic ignition. It would seem like fuel as it doesn't hunt like if it was missing a spark.
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Re: Power loss

Postby 1972nail » Thu Jul 05, 2018 3:59 pm

I think you already have bypassed the resistance wire and fitted a 12v coil, but just in case you haven't here's the link.

viewtopic.php?f=12&t=22328&hilit=bypass#p86522

Have you checked the tank vent pipe? if it's blocked there may be a temporary vacuum which will cause starvation.
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Re: Power loss

Postby Mike Attew » Thu Jul 05, 2018 4:14 pm

The coil resistance lead has been bypassed but I did find a couple of days ago the wire end was green and it seems to have been just pushed into a connector on the bulk head, the one with 2 white wires leaving the red connector so I have now soldered it BUT I will now check the wiring diagrams because the resistance wire may be on this circuit.

Good thought about the vent pipe though, will have to give it a check.

Just that it's so random. Another thought I had is heat messing with the fuel.
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Re: Power loss

Postby Mike Attew » Thu Jul 05, 2018 5:01 pm

Just checked the wiring diagram but also Paul D thread and he swapped the wires from D4 to D5 on another sugestion so I presume the resistance wire was bypassed like that but the feed from the block to the coil was also bypassed in the engine bay.
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Re: Power loss

Postby droopsnoot » Thu Jul 05, 2018 6:33 pm

Is the fuel filter OK? I hear of some breaking down internally and I wonder if that could restrict fuel flow. I'm keeping an eye on mine, especially now that I have a filter on the pick-up pipe in the tank, and technically can do without the extra one.
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