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I was having a similar problem and it was due to leaking injectors.

You should hook up a scanner and take a look at the BLM and O2 values. Also check the fuel pressure at the fuel rail, it should be 40-47 psi with engine rpm above idle.

 

Did you have a custom tune done on the Ecm? I would start with ignition stuff first also check gorunds on the car .. Check alt output i had an astrovan once when throttle was stepped on fuses blew turned out alt was putting out way too much ..Could just be a rubbed through wire on tach side thats why fuses is popping.

 

hey thanks i will check into that i also noticed that when i put the fuse in sometimes it lasts awhile before it pops but it runs terrible like jerkin and surging

 

anybody?

 

Check the injectors as suggested, then check for vacuum leaks. I know the 24# injectors won't make it run rich, even without a tune. You might want to clean or replace the 02 sensor, it's often overlooked. With a problem like that you have to be getting a check engine light, if so, find out what they are and let us know.

 

I would bet that the stutter and popping fuse are related. Go through the ignition wiring and see if you can figure out what's wrong with the tach. I think that's where your trouble lies. The tach circuit can short out taking the PIP(primary ignition pulse) with it.

 

I will do that in the am, the tach is not even hooked up, msd ignition is just hacked together i have never seen something so hacked together in my life. i think there is a whole roll of electrical tape on there. I think im going to just take it all out and wire it back to stock, thanks for the input.

 

The MSD is a helpful addition to a highly modified engine. But like anything else, it has to installed properly and as part of a well thought out ignition system. Otherwise it's nothing but trouble.

 

well I surely do not think it is installed properly since it is all hacked together and now i don't know what wire goes to where to put it back to stock. Just for trial and error u know. would you know where to find a wiring schematic for the Distrib. to coil and the other set of wires on the coil. I just need to know what wire goes with one another. Since as you know the P.O. was too lazy or cheap to do it the right way with the plug and play application. He hacked into and spliced everything together, with multi colored wires. The 2 coming off the Distrib. are both skinny white wires? Please help....

 

You can find diagrams at austinthirdgen.org. I would post a link if I knew how but just enter it in google search and you'll find it. i am currently building a better diagram library at eaglemark.org DIY efi, but I haven't gotten to the ignition wiring yet. They may have it over there though from someone else. Look for the link on my "wiring diagrams" thread on the Electronics forum.

 

A bad CTS will make it run really rich and exhaust will be black.

 

24 lb injectors without a tune will make it run a little rich. I had to use an AFPR and turn down the fuel pressure on mine. Car has more power a little leaner anyway.

 

I figured that but it runs alota rich like burn your eyeballs rich

 

Well I think my problem lies in the ignition, its a mess... as soon as i find what wires go where I will be taking out the msd box and hook the tach back up and see if that helps if not its for sale.

 

A serious ignition misfire will create sooty exhaust just like a rich condition from unburned fuel hitting the hot exhaust manifolds and/or catalytic converter and partially burning.

 

I have 1986 305 TPI running rich as well, not as rich as yours but pretty rich... any way to check the injectors to verify they are bad? O2 sensor checks? Or just replace them and move on to the next step?

 

The only way to test injector output on car is the injector balance test. In this test, we charge the fuel system with pressure, the regulator and check valve must not leak at all, then we use a balance tester which is basically a timed switch which activates the injector for a specific period of time, generally less than one second. Each injector is tested while pressure drop is monitored during each test.

Any injector which drops pressure faster or slower than the rest, is marked as a possible problem unit. Since most vehicles do not solidly hold fuel system pressure due to leaky check valves or regulators, this test is of marginal value. e generally rely instead on a cylinder power balance test with compression and ignition integrity verified to isolate likely injector issues. the balance test is still useful to find glaring injector problems. The preferred method for testing injectors is to remove them and have them flow bench tested by a specialist. Flow testing and balancing is a standard part of an injector service.