So I'm looking at buying a 94 coupe/auto with 53k miles. Seller replaced optispark, throttle position sensor, and water pump in last 2 years. He says cars was running fine, then he added some fuel additive and now starter cranks over but no start. He says he starts to smell gas, but can't see any visible leaks.
I was thinking I should check fuel pressure at rail, possibly the filter has become clogged? How do I best check spark?

Any other suggestions?

Thanks in advance

 

put a fuel pressure gauge on it and pull a plug wire and look for spark they will take it from there. how old is the gas?

 

antfarmer is right - easiest way to check for spark is to pull a spark plug wire (probably Cyl No. 2 or No 4) an have a friend crank it over.

I HIGHLY doubt that the no start problem is related to anything that was added to the gas tank... Do you hear the fuel pump run for a couple of seconds when you first turn the key to on ???

 

better for you to crank it and have your ( friend ) hold it.

 

I also doubt the fuel additive caused an issue. Definately check for spark first. Take plug wire off, doesnt matter which. Put a screwdriver in the end of it making sure a tight fit. Then lay the screwdriver metal part right next to something metal, I mean with a hair of it, then crank the motor. You can place it where you can see it thru your windshield, and you do not need someone to hold it. If you have spark then most likely its a fuel problem. Take off your air filter intake hose off the throttle body, spray a couple squirts of starting fluid in the throttle body and try to start it. another thing you can do yourself. If it try's to start, its definately a fuel supply issue.

 

Verify spark, put a pressure gauge on the rail. That will paint you a picture.

 

Check the vacuum hose for the FPR to make sure there is no fuel in it and it flooded the engine. If that is OK, then sounds like injectors are pumping fuel into engine but probably has no spark. Easy to check for spark off the coil itself.

These things you can do without any special tools.

 

How can I be sure its not the injectors? The seller said a mechanic told him they need to be replaced, but I suspect the mechanic is just guessing.

Thanks for all the advice, I am going to try and see it this weekend.

 

Is it possible that the injectors aren't working - sure it is. But the way you check the injectors is quite a bit more complicated, and the odds that enough injectors are bad that the car won't start or even attempt to start is pretty darn low.

OK - There are several diagnostic tests for injectors... The easiest is to pull the connector off the injector and to use a meter to measure the resistance of the fuel injecor coil. But all that tells you is if the coil is "good" (read that as the coil in the injector not being either open or shorted) - it tells you nothing about how much the injector is flowing or what the spray pattern looks like. To test either of those things - you need to pull the injectors off the engine, and either design and build a test rig that will feed the individual injectors fuel at about 45 psi, and allow them to discharge into a clear container where you can see the spray patters, and measure the output for a given amount of time - or to send the set the injectors out to a rebuilder who already has such a test rig. Most of the time when someone says the injectors are "bad" it really means that they are clogged up, and not spraying properly - as opposed to not operating at all.

One other test to see if the injectors are being told to fire involves getting a set of "Noid lights" that you hook the wires that normally go to the fuel injectors to temporarily, and when the PCM commands the injector to fire - the noid light lights up. BUT - on the LT1/LT4 cars, the computer gets a signal from the distributor that tells it the engine position - and if you don't have a spark - there is a decent chance its because the optispark distributor isn't sending that signal to the PCM, so the PCM doesn't think the engine is turning over.

Again - start by verifying that you have a spark at the spark plug - and that you have sufficient fuel pressure.

 

The 94 injectors hold up well unlike the injectors before the 90s. Changing the injectors is I think a bad guess and indicates he has not really ever looked to see what the actual problem is. Seems like he does not have to skill to do it and is troubleshooting with a 10 foot pole.

An injector or two might cause poor running but hard to believe 8 are bad overnight and would prevent the engine from starting. You have to get some basic data to see what direction to start in. I would think if you listened to the 2 second prime when you turned the key you would hear the fuel pump run.

Think about it, if the injectors were all clogged up, why would you smell fuel? (And the engine not start).

 

Diagnose before spending any money on parts. If u cant find the problem yourself then the first $100 u spend should be a diagnose at the dealer - yes they will still take your vett in and usually that diagnose fee will go to the repair they make.

For checking spark u can use one of these ($7): http://www.lislecorp.com/divisions/p...n=1&category=8

Most auto parts stores have fuel press gauges they will loan u. That is critical here to make sure u have fuel press (~40-43psi). BTW when was the fuel filter last changed.

U can observe the injectors by pulling the injector rack up on top the intake manifold and crank the motor - u will want something to catch the fuel that sprays out. This will only tell u if all the injectors can spray and not clogging - nothing 'bout flow characteristics.

Enough for now, let us know what u find.

 

I went by the parts store Thursday night and confirmed they have fuel pressure kits. I may go ahead and buy a fuel filter since it is returnable. The car is on the north shore kind of remote, I'll swing by the parts store before I go, if I can't start it I have to figure out a flatbed to the city, which I'm sure will cost me. Good to know it's probably not injectors, sounds like he had some bad advice. I''ll be ready to check fuel and spark and report back!

 

the fuel filter is a pita on it easyer to take the line off the back of the filter and on the return line and take it out the top. make sure the fuel is low or disconect the lines or you will get a bath.

see if they have a noid light too.

 

This is great advice. But (Beachfreak) I think you are wasting your time with this particular kind of problem thinking a filter is bad. Clogged filters happen slowly and effect high volume fuel demand of power first. Like at high speeds.

I would put checking for spark off the coil first on the list. Followed right behind it checking fuel pressure. IMO

If there is spark and fuel pressure, then check injector pulses.

 

 

Fuel pressure went to 41 psi, then higher while cranking. I pulled codes, and only got H32, H34, H36, H38 all with a small 1. Then it went 4. ,then 9. With the three dashes showing, then A with three dashes then 1.0 and just stayed there. Now what?

 

Used a spark indicator on 3 different plug wires, they all were getting spark

 

look at the codes they are all a short to a ground. shoot some starter fluid in it and see if it farts.

did you bring the noid light? if you have a ohm meter ohm the injectors.

 

They did not have a mood light when I arrived this morning. I have an ohmmeter in the fuel pressure kit. Not sure how to check injectors. True, codes seem to be historic ground issues, but no current error codes showing

 

just take the injector wires off and stick them in the injector they should all be close to one another. but shoot some fluid in first and see if it fires. noid light.