1990 indy engine problems

55nomad · Post by **55nomad** » Thu Dec 13, 2012 4:44 pm

hello all I have a problem. 90 indy 3.1
was working on the a/c replacing all componets. drove car for three days after when it started spurting and losing power. it has gotten to the point where the car barely starts and runs for only a min or 2.
so far i have replaced the fuel filter fuel pump twice, map sensor, fuel pump relay fuse(located next to the map sensor) ignition module all 3 coils plugs and wires and the computer. any help ... any would be greatly appricieated.
thanks paul

Post by **3X00-Modified** » Thu Dec 13, 2012 5:45 pm

Unplug the one injector that is visible on the right corner of the intake next to the TB... see if it starts then. The injectors when they go bad short out the entire bank which results in the engine not running at all.

scd88ga · Post by **scd88ga** » Fri Dec 14, 2012 5:35 am

Are you losing spark or fuel when the engine dies?

ronaconda · Post by **ronaconda** » Fri Dec 14, 2012 2:49 pm

Did you get a check engine light at any point while it was "running"???

Rettax3 · Post by **Rettax3** » Wed Jan 23, 2013 5:12 pm

Okay, I realize that this is an older post, but I am left shaking my head here. I'm not trying to belittle anybody or be a jerk (I can do that really well without even trying though!), but let me start off by saying that diagnosing a problem like this shouldn't start with throwing parts at the engine -try actually diagnosing the issue first. Do something like this:

-Determine if the problem is fuel or spark related -it is unlikely to be mechanical if the car was running good one day, then bad the next -if there is a lot of bad noises coming from the engine though, mechanical could likely be the culprit... First step is making sure all fuses related to the engine are good, connectors are all plugged in, nothing is obviously amiss -don't forget the fuel-pump fuse on the firewall when dealing with an older Beretta like the Indys, and check the level and condition of the oil. If there are any codes showing (check engine light illuminated) -check those, they aren't all that helpful on the OBD-1 systems, but they might direct you to the problem -stick a paper-clip into the two upper right-hand connectors on the OBD port -or buy a $30 tool that does the exact same thing as the paperclip, but looks better doing it

.

-Spark is the cheapest to diagnose -buy an inline spark tester, they're less than $10, usually about $5. Go post-to-post on your coils or plugs (whichever is easier to access and see), to make sure you have spark. Make certain your plugs are connected to the right coils! How much did you spend replacing the coils without fixing the issue?
-If you have spark, go to fuel. But, if your spark is weak or inconsistent (we know it isn't non-existent if the car starts at all), if it is just one coil acting up, replace that. Otherwise, consider the ICM or (with your year car) the CKP (7x Crankshaft Position Sensor -located on the back of the engine block on the V-6s and easy to get to from underneath). Check to make sure the wire from it to the ICM wasn't damaged or allowed to rub on the accessories or serpentine belt -especially with recent work done in the engine-bay, and make sure the insulation on the wires is still good on a car this old. Also pull the two-pin connector with the pink/black wire and the black/white wire and check the latter for good ground continuity -this will require an Ohm-meter or multi-meter, they can also be bought cheap if you don't want to invest in quality -I have some Harbor-Freight cheapys for back-ups I've picked up for $5 or less on sale, and they work adequately.

-Now on to fuel. If the spark checks out okay, buy a fuel-pressure tester. Actron makes a really good one for ~$50, but if you can't spend the money, they can be borrowed from Autozone or the like. Make sure you are reading the pressures at static (ignition on, engine off) AND dynamic (engine running), to be sure your car is getting fuel pressure at the rails -this also shows if you have a clog in the system that will allow enough fuel through if the injectors aren't firing but not enough to run the engine properly. Watch for a slight pressure-drop after the engine starts, and it should raise a little as the throttle is opened up. Issues to look for here are a bad fuel-pump relay or fuse if no pressure at all, a bad pump with insufficient or no pressure, a bad FPR (Fuel Pressure Regulator) if too high or too low a pressure. A bad injector may also cause too low a pressure. On your car, you want ~40-47 psig.

-If that still hasn't fixed your problem, you may have an injector problem or potentially a sensor issue. The MAP sensor was a good call, if you've already gotten to this point. Try pulling the spark-plugs and reading those -are they wet after the engine died? are they covered in black soot? do they smell like raw fuel? These all point to a super-rich condition or dribbling/leaking/stuck injectors. You could also have a bad ECM. Now here's a trick on that, and something you should do now if you haven't fixed your problem yet -pull the ECM cover off from under the dash on the passenger-side, and use a multi-meter to check for a good clean ground from the car to the ECM case, now unplug the O2 sensor, and check again. If you have a bad ground, recheck to make sure you didn't remove or break the ground-wires on the front of the block at the transmission-to-engine bolt.

I don't mean this to be a step-by-step end-all-be-all diagnostic guide, but it would certainly help to narrow-down the problem. I'm also not trying to slam anyone, but spending time actually looking for the problem rather than spending time trying to hit it by throwing darts at a board in a dark room also helps prevent wasting a bunch of money on replacing parts that weren't broken.

I highlighted the three most probable causes for the symptoms you've described, but without taking into account the work you've already done, just for reference.
Good luck.

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