9 replies to this topic

[lewBlew]

Hello and happy new year everyone!

 

A problem arose with my Mayfair on N.Y.E and hasn't gone away.. It's started to lose power and stutter when accelerating at low speeds (e.g. 1st/2nd gear) especially up hills, but not always so I;d class it as intermittant. Once it gets some momentum behind it it's fine. I can get to motorway speeds and has plenty of torque while there, it's just speeding up from slow where I have the problem.

 

Also if you keep your foot on the gas when it's mid-stutter it will backfire (think it's through the exhaust but not 100% sure). It also seems to make a loud pop noise sometimes if you floor the gas for a moment and then ease off suddenly.

 

I checked the timing tonight and it was well out. Strange because I haven't touched it. At 1500 RPM and with the vacuum hose - which is working perfectly - disconnected and plugged it was reading off the scale so I moved it to 8 degrees BDTC. This hasn't made much difference, a little but not much.

 

The car is a 1991 Mayfair 998, completely standard except for Powerspark electronic ignition.

 

It's not the dashpot as this is topped up. I've been told it's probably the weather (car is used to being garaged but hasn't the last few weeks) however I'm not convinced as it's never been like this before in the wet and the dizzy and rest of the engine bay is dry.

 

Any ideas?!

[M4TTD05794]

I had this problem (usually when the engine was cold), I never figured out what it was. It went away after I changed my plugs, leads and dizzy.

[lewBlew]

I had this problem (usually when the engine was cold), I never figured out what it was. It went away after I changed my plugs, leads and dizzy.

 

Cheers. Car is due for a service and I'm going to do it this month.

 

I was just worried it may be the head gasket or something as I heard backfiring is a symptom. It is losing water but I've put this down to a leaky radiator..

[sledgehammer]

Has it got points ?

 

sounds like they need replacing & condenser , also check dwell angle & timing

 

clean cap & rotor arm & a bit of wd40 on leads

 

maybe an idea to change to electronic - & save the hassle next time

 

check the dash pot has some oil in it as well

 

best of luck

 

Ps if you suspect head gasket - get someone to do a compression check 

Edited by sledgehammer, 02 January 2014 - 10:47 PM.

[lewBlew]

Has it got points ?

 

sounds like they need replacing & condenser , also check dwell angle & timing

 

clean cap & rotor arm & a bit of wd40 on leads

 

maybe an idea to change to electronic - & save the hassle next time

 

check the dash pot has some oil in it as well

 

best of luck

 

Ps if you suspect head gasket - get someone to do a compression check 

 

No it has leccy ignition already and the dashpot is topped up. Will investigate the leads, cap etc, thanks.

[JamesleppAFC]

hi i have this problem just wondering if you found out what the problem was?

[lewBlew]

Well I took out the plugs and leads and had a look and couldn't see anything wrong. Gave them a little clean up and put them back. Same with the distributor cap, but again it looked fine and dry. I filled up to the brim with petrol, and the problem had gone the next day.

 

So.. I really don't know.. one of the above worked, or the change in weather as it's got less damp?

[Seba5tian]

Mine seemed to have this problem really bad in cold weather, the backfire was coming from towards the front of the engine/exhaust manifold.. Changing the needle to a richer one (which i needed to do due to installing stage 1 exhaust kit) and filling up the dashpot got rid of all misfiring and it's been perfect ever since 

[jaydee]

HT circuit has nothing to with this.

LT circuit may cause this instead, like loose coil connections, bad earth etc..

Also some crap in the jet may temporaly block it causing the issue, worth a clean.

Edited by jaydee, 10 January 2014 - 07:22 PM.

[dklawson]

As Jaydee said, more likely to be low tension than high-tension components but with this being electronic ignition and since the timing was adjusted... probably fuel related in this case.   For future reference, if you have a tachometer fitted, glance at it the next time the problem is happening.  Most ignition problems can be observed by the tach acting oddly while fuel problems do not directly affect the tach.

 

With the timing correct, backfires through the carb are almost always fuel starvation related.  In addition to backfiring, fuel starvation may be accompanied by "surging" of the power under load... where the car feels like it is accelerating, then falling behind.  You probably have an HIF carb which will make checking the fuel level in the carb difficult.  As insurance against future problems you may want to start by replacing any and all fuel filters that have been installed.  If after this the problem comes back, consider replacing the carb's float valve.