Merkur Troubleshooting

I am trying to get my XR4TI running without much luck. It sat for approximately 5 years before I got it. 
It will start and idle roughly, giving it gas will cause it to die unless you feather the throttle a bit to get it to rev. When it does rev the turbo spools up very quickly (in neutral). Trying to drive it just makes it bog. 

So far I have resealed the injectors and flushed them out (the orings were leaking). Changed the fuel filter and the TFI module with no change. 

I did replace the timing belt and the marks were lined up, I have not checked the timing. 

The hose from the turbo to throttle body had some cracks so I wrapped it with tape so see if there was any change, there was not. 

I have not checked fuel pressure but both pumps are running. 

Check ignition timing?  Turbo spooling without load makes me think it might be retarded and not advancing.  If you can get it idling, try unplugging the VAM and other sensors one at a time to see if any of them do/do not change the way it runs.

I tried unplugging the VAM and it didn't change. I'll put the timing cover back on and check the timing.

I'd be wondering about whether the injectors are flowing, but I admit it's substantially on theory:

• It can't fuel appropriately for load, so no power
• slowly adding throttle with no load gets it to spin up, where it'll be more forgiving of fueling issues, but...
• running lean burns slowly, which might act like retarded ignition w/regard to turbo spooling?

I'm not sure I'd be tearing the injectors out and sending them off for cleaning based on that line of thought just yet, but five years is a fair amount of sitting. Maybe even just a bit more running with some fuel system cleaner would be a cheap not-too-much-waste-of-time? Got an ultrasonic cleaner you can toss the injectors into for knocking the chunks off?

Checking fuel pressure and volume seem like good tests that involve less tear down and money before pulling injectors. Not to mention the timing, as you guys have already noted!

Dumb question, just because I literally went through this last weekend on the project rx7 I'm trying to sell, but did you drain the gas?

I last put gas in the car over 5 years ago, and what came out of the tank didn't smell like gas, and it's a dark green color.   No wonder the car barely started and wouldn't stay running.  Well, that and the fuel leaks that I fixed :)

I siphoned most of the gas and added some fresh. I got some nasty dark brown gas out of the injectors when I flushed them but they could probably benefit from professional cleaning.

I am, of course, on tenterhooks 'til we find out what the actual fix is.

I will hopefully get back to it before the weekend. I started putting the timing cover on and couldn't find the bolts for it so I went on to other projects. I'll finish that and verify the timing and report back. 

Make sure that it advances with the timing connector plugged in after you verify base timing, I learned the "fun" way that if it's not getting enough voltage it won't advance at all.

Injector issues aside I would be looking for a vacuum leak. Maybe a smoke test of the intake?   

Have you done a compression test?   Is this a timing belt or timing chain motor? I would verify that the cam is in proper phase with the crank. 

If I knew at one time you picked up a Merkur, I completely forgot.

Do you has a build thread going on said specimen?

If it always bogs at high throttle openings, check fuel pressure.  Even if you can get it to rev to 5k at light throttle, if you snap the throttle open and it bogs and drops rpm it's likely a fuel pressure thing.

Spitballing here:

Put a full 12 volts to each injector as its running, one at a time. This will run each injector "wide open", and hopefully clear it out. Do them one at a time at idle with jumper wires. Also, fuel filter. Simple stuff first.

When I read the thread title I thought "that could be useful to me" then noticed that I started the thread...

Since then I have done nothing except push it into the garage Friday so some work can start. I tested the fuel pressure regulator with my harbor freight vacuum pump and it bled down. Then I took the vacuum pump off and plugged it with my finger and it still bled down so I thought maybe the vacuum pump was bad. 

It has a new fuel filter on it. I guess it is finally time for me to buy a proper fuel pressure gauge. 

I have a build thread somewhere, I'll find it later and update when I start work. Now that my daily is fixed and I have another new daily and my garage is fixed and organized I can start working on the fun cars (when I get a heater).

Edit: Here is the build thread, you even posted in it Brian . https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/88-merkur-xr4ti-rally/129712/page1/

It seems that the pictures have been lost to photobucket, I'll have to take some more. 

In reply to EvanB :

Well the internet doesn’t lie- I sure did post in it!

Thanks for the link 

 I guess it is finally time for me to buy a proper fuel pressure gauge. 

Forget proper, just buy the $17 Harbor Freight model (after 20% coupon iirc). I've got 2 or 3 kicking around and never had problems with those. Don't buy the big master set  from HF though. Too many issues. I bought one, exchanged it and the 2nd one still has issues. 

In reply to Vigo :

I missed that before. They label it as a fuel injection pump tester and it didn't show up in a search for fuel pressure gauge. Guess I'm stopping by harbor freight soon (convenient when it is only a couple blocks away).

Dose this car have a CAT?

I went through similar scenario, heard pump whine at the usual volume so didn't check pressure. wasted a bunch of time on other stuff & finally checked and got low reading.

dropped the tank to replace pump and found the short stub of hose within the hanger from the pump up to the feed line had rotted out.

I've had this happen twice in recent years on two different vehicles.

Donebrokeit said:

Dose this car have a CAT?

I believe so

I have a new fuel pump for it, just haven't felt like dropping the tank yet.

I had a buddy with an SVO that wouldn't run quite right. It turns out his turbo was wasted, and it wouldn't turn right under pressure. He did a bunch of stuff to it, then swapped the turbo on a lark. It ended up being an easy fix that a lot of hard stuff led up to. 

A plugged CAT could cause issues and as another member said a bad turbo can cause like issues. Might be worth unbolting's the CAT and see if there is any change.

I have a fuel pressure gauge you could borrow.

I am a little appalled that nobody has suggested to put a fire under it yet.

Knurled. said:

I am a little appalled that nobody has suggested to put a fire under it yet.

That should happen naturally, no need to go through the trouble of putting it there.