1995 had 3 different computer control systems and 2 different fuel injection systems. We need to know which set up you have. First, does your engine look like this:




And second, does your distributor cap look like this?

 

yes and yes what i have it the be what I found out here is the beloved obd 1.5 and after reading my post i have replaced the tps and clean the egr and replaced the gasket with the screen in it ,new temp sensor the one blow the thermostat.thanks very much

 

1 Does the check engine light come on and go off when you start the engine?
2 Does the check engine light flash or stay on?
3 Have you retrieved trouble codes? If so, what are they?
4 How old, and what brand is the distributor cap and rotor?

 

the cel is on at this time do to a bad o2 sensor bank one try to find a y pipe the previous owner wielded the o2 in and put after market wielded on cat that is rattling and has a hole in it.i one time had a p1345 they cleared the code and it hasn't came back after that just had it check last week and the only code was the o2.The cap and rotor are acdelco 1 month old and the wires are msd 4 month.sorry taking along time to reply computer is run real slow i thank the computer are out to get me ha ha thanks.

 

P1345 means the distributor is off at least one tooth. The DTC sets when camshaft retard is off ~27 degrees or more. If the distributor has not been reset since the codes were cleared, camshaft retard is off, and it's close to setting the code. If it's that far out of spec, you've got crossfire going on inside the distributor cap, and that would explain the poor mileage.

Camshaft retard is viewed on a high dollar scan tool, the el cheapos can't access the streaming data. It is adjusted by slightly turning the distributor. From the factory, the distributor will only allow ~15 degrees total adjustment, so if it's off close to the 27 degrees necessary to set the DTC, the distributor will need to be reset. Spec is zero degrees plus or minus 2 degrees.

 

I was think the same thing and have check with some of the local garages a round here and the say that as long as you have the time right on the marks the computer will relearn on it own.that is not right what i have read on here? so I guess I will go talk to the dealer here in town who is crazy high on prices.but after i do the fuel test tomorrow i will try to check the timing see if ever thing lines up right and by the way does the motor need to be cold to do the psi test at the filter.thank again captain for the help if it wasn't for this site I thank I done shoot this blazer and put it out of it misery

 

Couldn't be any farther from the truth. Absolutely false. Rotating the distributor does not affect ignition timing, it is controlled 100% by the PCM. If the crankshaft position sensor or timing cover are moved, removed, replaced, or disturbed, it will affect ignition timing, and a relearn must be performed, it will not relearn by itself.

As the crankshaft rotates, the crankshaft position sensor generates a pulse signal and sends it to the PCM. From the pulse, the PCM calculates exactly where each piston is, and what cycle each cylinder is on, (intake, compression, power or exhaust). The PCM sends a pulse signal to the ignition module that is modifed to include ignition timing advance. The ignition module sends a pulse to the ignition coil, and the coil sends the spark to the distributor rotor. All the distributor does is direct the spark to the cylinder it needs to go to.

The camshaft position sensor, (inside the distributor), needs to be aligned with the camshaft. The adjustment is called "camshaft retard"** and it's done by rotating the distributor. When camshaft retard is within specs, the terminals on the distributor cap are positioned so the rotor is aimed at the correct terminal when the ignition coil fires. When the PCM increases ignition timing advance, the gap between the cap and rotor increases. If the distance is too great, (incorrect camshaft retard) the spark can jump to the wrong terminal and the engine will misfire.

**As far as I'm concerned, a more accurate term would be "camshaft position sensor alignment".

No, it does not. When the fuel pump shuts off, fuel pressure will naturally drop slightly. If the engine is hot, heat under the hood will cause pressure in the fuel lines to increase giving you a false reading at the service port. If the fuel pressure increases to regulated pressure, the regulator will send the fuel & pressure back to the tank, and you'll never know it. In other words, the rise in pressure could mask a leakdown problem. When checking fuel pump maximum output pressure and leakdown at the filter, heat is not an issue.

 

just finished psi test at the filter key on pump priming 80 psi, pump stop presser start to drop to 50 psi in lesser than two minutes after 10 min held at 25. so by whats going on bad fuel pump? so do I need to change the sending unit too my gas gauge still work it floats some is that normal.And what you said on the time is what I've read on hear.Didn't get a chance to check the timing but was wondering i have this weird knocking noise in the bell housing though it mite be a crack fly wheel so took the cover of and couldn't see any sign with out separating the motor and tranns was wounding if the knock could be the distribute gear worn out and trowing the timing off.thanks

 

80psi is good, but dropping to 25psi after 10 minutes is too much leakdown. The problem is definitely in the tank. There are two possibilities: 1. Could be a bad check valve in the pump, which means it's time for a new pump. 2. There is a short rubber line that goes from the pump to the module, with a hose clamp on each end. It's possible the hose is leaking or one of the clamps is loose. Either way, the pump has to come out to find and fix the problem.

 

You say flywheel, so I'm assuming manual trans? Is the knock constant or only when you push down on the clutch pedal?