Well the engines back in but....MFI problems

[signature65]

Well after I had the top end done on my 73 I got the engine back in and after messing with the timing a bit got it fired up. Its quiet, runs, and has no leaks so far.....however......

While my MFI was out I did the CMA on it and adjusted all my throttle plates, stops, air correction screws, and what not. It now wont run above 4k RPM without lots of sputtering and hesation. I dont have a CO reader so I am cautious to mess with the mixture screws. But I do have some black smoke....which of course means rich....but it only puffs out around 3K RPM.

I had no problems before so I am not thiniking fuel pressure. Maybe ignition...points or something?

Thanks in advance

[tobluforu]

I would first take your synch and make sure the stacks are calibrated evenly at idle and then at 3000 rpm. Then I would adjust part load making sure you know how many clicks you moved it lean or rich. Also, spray some carb cleaner/etc around the stacks to make sure there are no leaks from when you installed them. Is the thermostat hose hooked up, points adjusted, etc..?

[signature65]

No thermostat as I have headders. Points are spot on, everything is sync'd up, I cant get it above 5500 rpm. I have followed Lee Rices advise and still nothing. I understand running rough or idleing horrible, but mine idles fine and just wont rev......

Maybe a major miss??? I pulled a plug and it wasnt wet at all. Black yes....but not wet. So i think its not set too rich that the problems Im experiencing are mixture related

[tobluforu]

But could it be too lean? I have tested my MFI with it being too lean and it would not run worth a crap after 3500 rpm-popping, backfiring, etc...
Worth a shot.

[356RS]

Darren, You said "No Thermostat"? because you have headers. Do you have a manual lever or something in place of the thermostat to control the warm up process of the MFI pump?

[signature65]

ya the thermostat was replaced by a screw with a quarter welded to it. So the mixture is easily fumbled with.

[signature65]

If I understand the thermostat properly....screwing in the quarter would lean out the mixture?

[356RS]

I remember your pump now. Yes, turn it in for a warmed up engine. In is lean.

[Rot 911]

Sure you lined up the dots on the MFI pump pulley and pulley off the cam when reinstalling the belt?

[signature65]

ya i timmed the pump with the engine out. So it was relativitly straight forward.

[911st]

I had similar problem w a 2.8 I converted to MFI.

Try double checking your MFI phasing.

I did this by removing #1 spark plug so I could hear the sucking sound during the intake cycle. You could also just take out all plugs except #1 to know the compression cycle.

Then loosen the injection fitting to #1 on top of the MFI pump. This will allow you to see fuel seepage when the injector is triggered.

Then turn the motor by hand...

[signature65]

911st: I like that idea, I will give it a shot. Exactly when should the fuel be delivered? right as the intake valve opens?

I really dont understand how my pump timing could be so far off. I swear I had it spot on. 400 degrees ATDC for cyl #1 and the marks lined up.

[Mr9146]

You got the injection plumbed right off the filter console?

[911st]

Yes, squirt is just as the intake valve opens or just before compression.

[signature65]

Ya I used the diagram in Bruce andersons book and the updated diagram by warren.

I have a feeling this is going to be one of those "doh" moments. Im working for the next few days so monday will be the next day I can tinker with it.

Keep the ideas comming guys, I really appreciate it.

[signature65]

Well I found a ground I forgot to tighten down all the way and voila I can now get full RPM. Knew it would be something stupid.

However its still running really rough in the middle of the RPM range. Backfiring and spitting like crazy. Im getting full advance. and it runs good now above 5500.

I pulled all my plug wires one by one and they all decreased the RPM so dont have any fouled plugs or misses. Any ideas????