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1995 Chevy Blazer starting issue

02-13-2010, 06:37 PM
First i have a 1995 Chevy blazer 4.3l vortec 4x4 4 door auto trans 71000 miles. Vehicle started not starting on first try always second for a few days. Then became very hard to start no fuel smell at all. Could start with a jump battery tests good alternator tests good. Was told fuel pump was bad not dead just weak. Changed this along with strainer and filter started fine first time once shut off if started soon after started but very choppy start cleared fast. vehicle volt meter on dash always below 12 that's why alternator was changed , have a 97 s10 pickup always above 12 never had any issues. Blazer with lights on and turn signal could see the volt meter move im not thinking that's good. Well today give it gas once slowing down engine became choppy for a few seconds went away. Well i got off highway and merged into traffic vehicle died check gages and battery light is on. Will crank will not start jumped no start, with key on theses two lights remain on normally once key is turned brake abs ses light come on theses lights are not coming on at all. Is this a charging issue bad ground or shorted wire or just a weak connection. Even before fuel pump was changed engine would not start off ether. What could cause this problem.

02-15-2010, 08:06 PM
Your 1995 most likely has CMFI but could also be CSFI. Which engine do you have?

This is a CMFI engine:

This is a CSFI engine:

Post which engine you have, then we can give you the procedure and specs for checking fuel pressure and leakdown, (the test procedures and specs are different).

Check battery voltage with a volt meter, (not dash gauge) with engine running at 2,000 RPM and all accessories off, and post your results.

What brand of fuel pump did you install?

Is the Service Engine Soon light on? If so, what Diagnostic Trouble Codes are stored? Autozone and Advance auto will check them for free. Write down the DTC's in the order they are retrieved and post them here.

AC Delco distributor cap, rotor and spark plugs? Don't waste your money on aftermarket stuff on those items.

Pull #3 & #4 spark plugs, (Middle plug on each side of the engine) and check for being wet with fuel.

02-19-2010, 08:35 AM
I have the CMFI engine there are no ses lights on no codes stored. Pump was bought at auto zone. Fuse ECMbatt was blown replaced started and drove fine but later that day gave the vehicle some gas and it blew the fuse again. I tried this again the next day no blown fuse only seemed to do it when volt Gage was getting low. Vehicle will start will good volts but as it warms it starts to drop was tested with nothing turned on but engine after warm, 12.2-13.00volts with heat lights rear defrost went to around 10.8-11.0volts. I'm going to replace alternator and see if it helps maybe i had a bad one. I'm hoping that anyways. Never really had problems with this vehicle before always started and ran fine only things failed were abs o2 sensors and egr valve. had voltage issues when i bought the vehicle Gage was always low replaced alternator 2.5 years and never really changed, battery was changed about 2 weeks ago old one had a dead cell. So i am stumped on this one once i change this alternator out ill post my results. As for wires I have Bosch, plugs are also Bosch, rotor and dist are auto zone most likely Bosch as well. Thanks

02-19-2010, 02:08 PM
From the sounds of things, you have more than one problem going on. The computer controls need proper voltage to operate correctly. Start with the charging system: Always check battery voltage with a volt meter, not the dash gauge. With the engine running at 2,000 RPM and all accessories turned off, check voltage at the battery and post your results.

Check fuel pressure and leakdown: Key ON, engine OFF, fuel pump running: fuel pressure must be 58psi to 64psi and must remain above 53psi for 3 to 5 minutes after the fuel pump shuts off. There are several threads on the forum that talk about multiple problems with brand new Autozone, (Airtex/Master) fuel pumps. Common problems are: leaking check valve, insufficient fuel pressure, insufficient volume, noisy and a short lifespan. The fuel delivery system is critical on the CMFI engine, not a place to cut corners using economy parts, stick with AC Delco or Delphi. After you check fuel pressure and leakdown, post the results and we can analyze them.

Bosch wires are ok but, the Bosch plugs are guaranteed to cause problems in this engine. Only use AC Delco plugs CR43TS with a gap of .045

Again, there are several threads here on the forum that talk about poor performance when using Autozone distributor caps and rotors, even when they're brand new, avoid them. Best to use AC Delco.

02-19-2010, 05:53 PM
Checked voltage when vehicle was cold first started 13.60v 59amps once warm jumps from 12.40-12.70, With defrost on high 11.20. Put new alternator in at idle it was at 14.90 after warmed up and 14.50 with defrost high, rear defogger on and lights. Have not tried to reproduce fuse problem yet will post once i drive it around a bit and see if anything happens again. Thanks

02-19-2010, 08:01 PM
No doubt the alternator was bad. Most likely it had a problem with the voltage regulator. Charging voltage might be a little high with the new alternator though. With a fully charged battery, all accessories off, engine at 2,000 rpm, voltage should ideally be 14.2 volts. Several things can cause charging voltage to rise above 14.2 volts: an open cell in the battery, a poor body ground, or the voltage regulator inside the alternator is set too high, (not adjustable). Most auto parts stores will check the battery for free. Locating a poor ground can be a little tricky, but with your DVOM, you should be able to find it, if it's a problem. If those items are OK, 14.5 volts won't hurt anything however, it might shorten battery life slightly. Keep us posted.

02-20-2010, 07:35 PM
OK did some driving today have not blown fuse so far only had radio and lights on though. Now i still seem to have a voltage problem vehicle in park or neutral can run any accessories and stays strong once in any gear drive OD reverse with same accessories on it will fall to around 12v give or take .5v. If i turn everything off but radio it will come back to 13.5v. But with lights on (night time driving) after about an hour will be around 12.5-13v shifts a bit when turning maybe .5v. If i turn heat on blower high will drop to about 11.9v rear defrost on 11.2v. put in park will bounce about 1v if idle in park for a few minutes will come back to 14v. But have not popped fuse so far. Is there any problem areas in theses charging systems to start my search. Was thinking of swapping the battery out of my truck just to be certain this battery is strong. Should i start on the ground wires first i know where some are at. Just seems to be a lot of draw on this system for some reason. Also once pump was changed out I'm having no problems with the vehicle starting it will start fine now just have this charging system problem odd thing is battery is not discharging at all. Have no fuel odor vehicle still averages 17-18 mpg city runs smooth idles pretty good before pump would misfire at idle no longer does this. Everything on this vehicle functions as it should except driver window sometimes will go down sometimes wont not sure if it has any contributing factor. Any parts i should check for wear that might cause draw on battery?

02-20-2010, 09:10 PM
Have you ever replaced the serpentine belt and belt tensioner? The spring in the tensioner weakens with miles allowing the belt to slip. The belt and the tensioner should be replaced around 50,000 miles. While the belt is off, check the idler pulley, alternator, water pump pulley, A/C compressor and power steering pump pulley for smooth, quiet operation.

02-21-2010, 09:29 AM
I have changed the belt maybe 15,000 miles ago but have not changed tensioner pulley. Noticed last summer it jumps around with ac on. Moves maybe a centimeter or less. Can move it a little by hand as well. But no squeaks or noises from any pulley water pump pulley still strong no wobble on it. I can take parts from my truck it sits next to it outside not going to be driving that anytime soon trans blew in big snow storm. But just don't no what I'm looking for. I can change that pulley if i need to you have more knowledge on theses vehicles than i do. So where you tell me to look i will look. So if you have any ideas please feel free to tell me. Could the wire be in that fuses circuit or voltage problem. I'm sure if i turn some accessories on it will blow again. But only under weak voltage.

02-21-2010, 09:38 AM
When voltage goes down, amperage goes up and that may be what blew the fuse...too much amperage draw.

If the belt jumps around, it's an indication of being loose. It can be caused by a weak tensioner, a stretched or incorrect belt, (too long) or one of the pulleys is not turning freely due to a faulty pulley bearing/bushing.

02-21-2010, 05:56 PM
Belt doesn't jump tensioner pulley does a bit. But today the fuse blew again this time voltage was not low was right on 14v. Could pump be overheating since i seen some of your earlier responses about auto-zone pumps. Could the pump also be causing my voltage drain. I listened to my belt and its smooth ac pulley makes a slight noise but no other pulley. Belt is fairly tight tensioner pulley has an arrow on it and base has to lines its not lined in between them. If i do change pump is there a name i should buy and names i should avoid or dealer pump? Thanks

02-21-2010, 06:41 PM
The line on the tensioner should be aligned with the line on the base, if not, the tensioner is weak or it has the wrong belt.

The ECM BATT fuse feeds several things, the fuel pump is one of them. If the fuel pump, or the wiring going to it shorts out, the fuse will blow. An internal short in the pump could cause this. What you have seems to be quite intermittent. To say the least, it will be difficult to diagnose, but not impossible. Typically with an intermittent short circuit, the suspected item is removed from the circuit to determine if it's the cause, but in the case of a fuel pump, that's not an option. An alternative would be to hot wire the fuel pump using a fused external wire and monitor fuel pressure while wiggling wire harnesses to locate the short circuit. If it blows the external fuse during this test, you'll know you've got the right circuit. Then it's just a matter of tracking it down. That will require a DVOM, (digital volt ohmmeter) and a schematic, which I can supply you with, if you need it.

02-21-2010, 07:42 PM
OK it happened again it only happens under heavy acceleration i felt the wires going over the tank and in threw the top and there very hot not just warm, enough to move your hand away. voltage still gets weak i think i may have two different problems doesn't seem that voltage and fuse have any thing to do with each other. So this fuse is popping under heavy acceleration only but not every time seems the new fuse can handle it for a short period. In my manual this fuse says ecm batt abs batt and fuel pump. Now id think the pump relay would also be off this fuse and i heard oil pressure sender as well. But yes the tensioner doesn't line up where it should but if i turn it there the belt will become loose. Also the tensioner body has a small crack in it. I'm extremely confused with this vehicle i take great care of it. I checked voltage on my pickup to get a base point as i know it works fine. It has stayed above 14v idle with everything i can turn on on. I just don't know where to start i know so many things can cause so many different results. You said remove things from the circuit i think the only thing easy to remove would be disabling the abs system which is fairly easy.

02-21-2010, 08:13 PM
Check fuel pump amperage draw on the grey wire while the pump is running. If the wires are too hot to hold, that's a problem, probably the pump.

If the tensioner is cracked, replace it.

02-21-2010, 08:32 PM
Its hard to check this id have to be driving to get it to fail again. key on but car off it starts around 3.9 and shuts down at 4.3. Car on idle 4.2, 4.3 doesn't really change with rpm change. Cant really check under load hard to reach theses wires unless i knew where they came in at and my meter can only read to 5 amps. I will replace tensioner should i change belt as well seeing if i line up new tensioner belt will be fairly loose.

02-21-2010, 08:39 PM
If you hot wire it at the relay, (make sure you use an inline fuse) you can monitor it there. Don't start the engine, just let the pump run. It won't hurt anything, the fuel will circulate from the pump across the injectors, through the regulator and back to the tank. The injectors will not open, (unless the engine is cranking) so it won't flood. The orange wire has B+ at all times and the grey wire goes to the pump.

02-22-2010, 05:29 PM
I'm picking up an ac delco pump tomorrow but don't have time to install until Monday. But once its in I will make sure to post my results I'm hoping for the best i really want to keep this car its in such great shape and low miles. I have pictures from the past and after driven the vehicle was right at 14v (took picture when getting an alignment for some reason after it comes off the machine alternator wouldn't charge battery. Low voltage always happened with rear defrost on. So I am hoping this fuel pump is causing my problems. Or my electrical problem started then.

02-22-2010, 05:45 PM
When you have the pump out, check the electrical connector at the pump module. There's a known issue with high resistance and the heat melts the connector. Most of the replacement pumps come with the new style connector and it should be soldered on to the vehicle harness. Don't use the crimp connectors that the new plug comes with. The old style connector is square, the new style is a flat oval shape.

02-23-2010, 07:44 AM
The dealer sells a new wire kit for it. Not the whole thing from front to back just a 2 foot cord from connector to connector I am gonna get that as well just so its new. I know whats under there has been out for 15 years and we get some crappy winters around here. So it wont hurt to change that as well?

02-23-2010, 06:12 PM
If all it needs is the connector at the pump module, don't bother with the wire kit from the dealer, use the one that comes with the your money.

02-24-2010, 07:31 PM
I'm going to be putting this pump in this monday coming up. There are no wires that come with the pump. Its a small pump and a couple little tubes and instructions. I know the newer pumps come in the whole assembly that spins on the top of the tank this one is just the pump that goes into that assembly. So pretty much the wires on the top are not changed. Im not sure how to explain it really what comes out of the tank the full assembly. The pump goes on the bottom of this assembly and everything goes back in. The wire kits they sell are for outside the tank. This new pump is in a rubber foam sleeve the one in it now is not in one these. And the pump sides are all steel. I have not gotten into it yet but i believe the small two wire connector that goes to the pump is submerged. I'll tell you everything i find out once i get in to everything to change it, I will also check all wires inside tank and on top for wear bare spots or any melting or just breakdown. I'll keep you posted on it and how it goes when done. I've been driving it fine as long as i don't give it to much throttle it don't pop that fuse. Thanks i will post when finished with it.

02-26-2010, 09:36 AM
I'm not sure if this has any effect on anything. But i was looking over the engine when i changed the tensenor pulley. I noticed some black soot on the intake manifold underneath the throttle and just behind the egr valve. I'm not sure if this hurts anything could egr be leaking a bit of exhaust Maybe not seated all the way. Tensenor didn't make no difference but i noticed there are two different sets of lines and two arrows. One set in center on top and one set off to the passenger side one is lined up one isn't. One off to the side is. I have no idea which set should line up or if thats a tolerance of how loose is to loose.

03-02-2010, 05:33 PM
Changed pump yesterday and still having same problem. It has to be an electrical issue this has not happened until pump was changed. Wires are fine no rips wear or bare wires. Any ideas are helpful if i cant fix this I'm scrapping the car.

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