Loss of power

Mike Schofield

Mike Schofield

True Classic
just changed the fuel filter which was pretty nasty and cleaned the air box before the filter. Took the car out for a run and now it seems to drop power off the line as well as through the revs...any ideas? Did I tighten the hoses too much? What did I miss??
 
I feel your pain Mike. Try doing what I've done lately, don't work on it. :oops:

"Air box before the filter"? Not sure what you are referring to.

Could some of the dirt in the fuel filter been dislodged in the replacement process, getting into the carb?
 
I believe it’s called the air flow sensor...my x is fuel injected. The other time I was working on it I ended up pulling a fuel injector connector and not knowing. I ended up driving to and from Toronto with it unplugged running on three cylinders without even knowing. Huge eye roll...
 
Ahhh, I get it. I assume you removed (or at least disconnected the hoses to) the AFM to clean it out. That might have given an opportunity for a vacuum leak (as NEG suggested) when reassembling things. This system is dependant on good vacuum readings, so any vacuum leak will throw things off; loose dipstick, loose hose connections, cracked air hoses (look around the big one to the AFM and the medium ones to the cold start valve, they get brittle), etc.

Also double check there aren't any fuel leaks where the fuel filter was changed. The FI system is reliant on high fuel pressure so a leak could allow to little flow volume under load. But you should likely see and smell the leaking fuel (it would need to be a lot).

Any disturbed wire connectors anywhere - like the time the injector got disconnected? Maybe the big one on the AFM for example?
 
Tip #1: If not familiar with where everything is supposed to be, take plenty of pix before!

Idea #1: Any possibility that the filter was installed backwards? Most filters will have an arrow of some sort pointing in the direction of flow.

Idea #2: I don't think whoever makes the current crop of FI filters does a good job, I had one where the actual filter element inside broke loose and was rattling around inside the can....obviously it couldn't effective filter squat-ta in that condition! If you eliminate the simple stuff like an inadvertently disconnected or otherwise disturbed connection, try a different filter.
 
Well, no loose connections. I think I’ll try changing the fuel filter back to the old one tomorrow and see what happens..
 
It is most likely an air leak. The fuel filter is unlikely to cause a loss of power, I would leave it alone for now
 
Agree, more likely a vacuum leak. Try spraying a highly combustible product on all of the hose connections, along their paths, etc to see if the idle changes momentarily. If there is a vacuum leak it will suck in the product and richen the mixture for a second.
 
That sounds like a good plan. I think I checked all the vacuum lines but I have been working around the intake and so on so...I also thought again about the fuel filter. It’s a wix filter from rock auto and is psychically the same as the old one...very unlikely it’s installed backwards and I haven’t had any issues with parts from rock auto so I think that may be chasing the wrong squirrel up the tree...
 
Starting fluid, carb cleaner, brake cleaner, propane, or any aerosol that is highly flammable. You should try to do it so the spray is contained in only the area you are inspecting. If the spray goes everywhere it will get sucked into the air filter and give a false positive finding. Naturally use all safety precautions. Maybe view a couple YouTube videos to see how others have done it if you are not certain. It isn't absolute but hopefully will show any obvious leaks.
 
Well, I checked the vacuum lines while the car was idling and nothing. The missing is still happening when driving. Sometimes off the line I’ll put my foot down and the car bogs down and will barely accelerate. :( Just another day in the life of an x1/9 owner....when accelerating it feels like the car wants to pull but then drops off and back on...
This car had sat for a while and when I changed the fuel filter the fuel to the inlet of the filter was brown so perhaps a fuel system flush over the winter is in order including the injectors etc...
 
Only under load does this happen? What about when the car is sitting in neutral and rev. the engine? Under load it is a demand issue, fuel flow. Static if okay I would say Injector fuel line blockage. There are little screens that are at the inlet of each injector that could be plugged.

TonyK.

Grimsby Ontario Canada.
 
Mike Schofield said:
Well, I checked the vacuum lines while the car was idling and nothing. The missing is still happening when driving. Sometimes off the line I’ll put my foot down and the car bogs down and will barely accelerate. :( Just another day in the life of an x1/9 owner....when accelerating it feels like the car wants to pull but then drops off and back on...
This car had sat for a while and when I changed the fuel filter the fuel to the inlet of the filter was brown so perhaps a fuel system flush over the winter is in order including the injectors etc...
Click to expand...

Clarification needed:
Was the lack of acceleration and bogging down happening before you changed the fuel filter, or after you changed the fuel filter, or was happening both before and after?
 
After fuel filter change. I should also mention that I had inadvertently disconnected a fuel injector connector and driven back and forth to Toronto before noticing and reconnecting it. So, not sure what the deal is....perhaps the disconnected fuel injector got its screen blocked?
The more time I spend with this car the more I’ve come to realize how finicky they really are. People talk about Italian cars but I thought it was just an over exaggeration. :( The bogging down and missing is only under load. She seems to idle quite happily.
 
The problem with the injectors on this car is that they are hose crimp connected. Normally what I would do is remove the injector then immerse the injector in solvent and then with compressed air reverse blow it a few times. Then forward blow with compressed air to see if it is leaking.

To pull the injectors the hose crimps need to be removed and hoses replaced. Kind of a pain to do, but may be what is needed to be done.

TonyK.

Grimsby Ontario Canada.
 
Exactly how long did your car sit? I'm thinking maybe you have bad gas with a high water content.
 
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