1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

[peterboat]

As the title suggests this right at my cruising at 70 MPH at a touch over 3000 RPM it really runs rough but will pull through it eventually which is rubbish.
I thought before I did investigations I would ask on here [I have had a new fuel pump as it failed] It starts instant and pulls well below and above this figure. I have had a quick look on forums that include this engine but no real help.
I did have a garage until last year so I am very mechanically minded
Thanks in advance

[dcunn]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

Phil, thanks for your comments in the other thread about the floor job

Peter I hope you won't mind me chipping it but it may be relevant here.

2.3 Ford engine, I believe same as yours, my tickover is around 1300-1400 rpm even when v hot. Should I try the reset as mentioned above ?

No problems with cruise or other settings, smooth and powerful.

Me, I'm ignorant on "modern" technology, so any thoughts please

Rgds DC

[peterboat]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

Yes high pressure pump. I will try the reset procedure Mine idles at 900 rpm on the tacho but sometimes idles higher when under load [fan on]

[philcoyle]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

To dcunn, "modern technology" was brought about by little old ladies who pulled out the choke cable in the morning to hang their handbags on, AND YES I know someone who up until recently did this in her 3.5ltr Range Rover, when I asked why she ignored the idiot light on the dash informing her the choke was still out, her reply was, is that what that is for!
She thought if you pushed the choke in ( but left the handbag/doglead on the cable) it was okay even if black clouds of unburnt fuel belched out the back.

[dcunn]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

I've never been a little old lady Lol

Guess I'll have to get past the Flintstone era and try it out, will let you know when I'm back on the road.

Rgds DC

[peterboat]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

Resetting the tps did nothing I am afraid still same problem 3000rpm gentle acceleration = smooth 3000rpm med-hard jerks coughs splutters eventually pulls through and it goes poo!!!

[andyf]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

Could it be a sticky air flow sensor. From memory they have moving parts that tended to get gummed up.

[peterboat]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

This has just started it ticks over smooth and up to 3000 perfik after 3500 perfik if under light load its perfik all the way very strange

[peterboat]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

Fuel pressure great same problem before pump failed Not any better or worse now. I was hoping it was the pump failing that was the issue plus I have fitter a filter pre pump now to stop it happening again

[Mike]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

Resetting the tps did nothing I am afraid still same problem 3000rpm gentle acceleration = smooth 3000rpm med-hard jerks coughs splutters eventually pulls through and it goes poo!!!

Using logic to solve problems does not always work, and I know very little about Ford engine management, but..............

Given your problem does not occur below 3,000rpm, or above 3,500rpm, how could it be fuel starvation (failing pump/pressure), or air(leak). In both cases the likely failure will get worse up, or down the rev range, not be restricted to a very narrow rev band.
The pattern of failure suggests a sensor that has worn in a critical position - move away from it, above or below and the problem does not exist.
Does the Ford engine have a Crank and /or a cam position sensor? These, along with the throttle position sensor, are common fail items in BMW engines leading to the type of problem you are experiencing.

Just logic and an idea.................?

[scott h]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

You don't say exactly what engine you have or what year the engine is. I know there was a 2.8 inj V6 and a 2.3 V6 but I am less sure it was injected. Anyway, if it has fuel injection does it have an ECU? If so there should be some way of reading fault codes.

[dcunn]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

Mine is a 4 cyl 2.3 DOHC injection, it's the old Scorpio engine, I guess the same as yours, here's an old pic.
Yes Mike, I believe they do have a crank sensor
Rgds DC

[philcoyle]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

DC with regards to your fast tickover, I can see that your accelerator cable is rather angular and possibly a bit short, it doesn't seem to flow very easily, maybe needs a little bit of attention and a bit of slack.

[dcunn]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

Thanks Phil, as per our PMs I'll get round to it once I'm de-Flintstoned !

[chris_cussen]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

The crank sensor on these engines can be found at about sump level at the back of the engine on the RH side of the car (as you sit in it) so it is the same side as the servo. It consists of a coils of very fine wire in an epoxy moulding. There is a 2 pin plug connected to it. If id does fail (and I have had one do so) it tends to be terminal. The only check you can make is to measure the resistance which IIRC should be about 200ohms.
It is very unlikely this component will cause your problems at 3000 rpm.
Replacements are available, I think I paid about £12 for mine.