OT Another car problem-no power to injectors

RAS · Mar 4, 2010

I have a 1988 Olds Cutlass Ciera, 3.8 multiport FI V6. Previous to sitting over the winter, it ran, although poorly. Now, I have no power to the injectors at all. I checked all the fuses in the glovebox panel, but all are good. The wiring harness disappears into the firewall, so I haven't traced back any farther than the six-contact plug that connects to the injector harness.

Does anyone have an idea of what the problem might be? I really need to get this thing running ASAP.

RAS

AIR-O-LATOR · Mar 4, 2010

Check crank/cam sensors if the ecm doesn't get a signal then the injectors won't pulse (noid lights work really well here you can crank and watch the injector pulse). If it ran poorly then there should be a code stored in the ecm to point you in the right direction. Oh check the grounds. The ground on the front of the engine by the starter is prone to breaking in the motor mount gets weak.

RAS · Mar 4, 2010

Ok, I'm in a shade-tree situation, and the only diagnostic tool I have is a multi-meter. Where is the crank/cam sensor(s), and can I check them? If nothing else, I can replace them just to eliminate that as a cause, but I don't know where they're located.
I'm not much of a cars with computers kind of guy.

RAS

viper · Mar 4, 2010

I will agree with above on the CPS.

However, how do you know you are not getting power to the injectors? Testing power to them with your multi meter? You do realize the pulse width is extremely short right? ie, your meter likely will not see it. You may need a scope for that.

Do you have spark? MANY times, when an injected vehicle goes down with a no fuel condition, it is related to the fuel pump. Check to see if you get a hum from the tank with the key on. Also might crank a fuel line before the injector bank to make sure you have fuel flow. Sure sounds like a fuel pump to me.

Get your codes checked. a wide pulse width error is usually found if the pump is dead. Those codes will certainly point you to a direction.

RAS · Mar 4, 2010

viper said:
I will agree with above on the CPS.

However, how do you know you are not getting power to the injectors? Testing power to them with your multi meter? You do realize the pulse width is extremely short right? ie, your meter likely will not see it. You may need a scope for that.

Do you have spark? MANY times, when an injected vehicle goes down with a no fuel condition, it is related to the fuel pump. Check to see if you get a hum from the tank with the key on. Also might crank a fuel line before the injector bank to make sure you have fuel flow. Sure sounds like a fuel pump to me.

Get your codes checked. a wide pulse width error is usually found if the pump is dead. Those codes will certainly point you to a direction.

Ah, I didn't know the pulse was that short; I'm lost with these cars. I do have spark and fuel is going into the injector manifold (spark at coil, and fuel comes out of the 'tire valve' when the stem is pressed). When a bit of starting fluid is sprayed into the air cleaner, the engine does fire.

RAS

The Energy Rebel · Mar 4, 2010

Coil pack.
Usually when one goes, might as well replace the other.
Not cheap.

Easy to check fuel pump (possible problem also) just listen for it to come on when you turn on ignition. You can also disconnect fuel line and see if it's pumping with good pressure. It should shoot a good stream.
Even if you're getting a spark, if it's not strong enough (white or blue) then it won't run.
If the fuel pump's ok, then likely coil pack.
I'm not 100% sure about your make and model, but they started going to those about the time yours was made.

RAS · Mar 4, 2010

The Energy Rebel said:
Coil pack.
Usually when one goes, might as well replace the other.
Not cheap.

I've got spark at the coil.

RAS

Ghost · Mar 4, 2010

Mice may have moved into the car for shelter over the winter, check the wiring for damage.

RAS · Mar 4, 2010

Ok, after re-checking, it looks like the fuel pressure is low; hardly any comes out of the pressure test valve when the key is on. I guess I'll replace the fuel pump first. Is there access for that through the trunk (trunk is packed full right now.)?

RAS

3t3d · Mar 4, 2010

What about a clogged filter?
Check before changing the pump.

AIR-O-LATOR · Mar 4, 2010

Fuel pressure should be 30lbs or so. I would put a gage on the shrader valve on the fuel rail to see what the pressure is. I agree with the filter first. Then check the pressure again. Even if the pump is out the ecm is telling the injectors to pulse if it was newer say 2000ish then fuel pressure would come into play on injector pulse. Thats where the noid lights come into play and they are cheap.

AIR-O-LATOR · Mar 4, 2010

One more thing try to get a service manual for the car. It will have the componet locator in it and the specs for almost each of the componets i.e. ohms on the injectors, fuel pump pressure,cam/crank specs, why sidepost batteries always leak even if they are new (kidding on the last one its a mystery of the universe) The manual will come in handy.

Greg Quenneville · Mar 4, 2010

Just be careful that you understand system operation before you assume the pump is bad. On some cars the fuel pump does not run until the engine is cranked, others the pump runs briefly when the key is switched to "on".

The best pump diagnostic would be a fuel pressure gauge check while cranking.

I just replaced a fuel pump in my Japanese car as it was cheaper than buying a pressure tester. In my case it was a good bet-problem fixed.

Are their any online troubleshooting resources for your car? If not, I'd try and find a manual on ebay.

Crank position is a usual suspect, as are corroded connections, including fuse holders.

watt-steam · Mar 4, 2010

Obvious but critical - if you haven't yet, check ALL fuses, check there is gas in the tank. Next check all ground wire attachment points to engine and frame/body.

mobile_bob · Mar 4, 2010

not sure about the olds, but 350 chevies when they went to multiport
require about 44psi to do the injection thing, if it gets much lower it won't inject.

the pump can sound fine, put out quite a bit of volume, but if the pressure is low, no dice.

a quick test i do on these systems, for a weak pump
once the engine is running is to hit the guage bleed valve on the tester
if the engine continues to run with the bleed losing fuel, the pump is good, if on the other hand i hit the bleed and the engine stumbles and dies, the pump is tired.

and of course replace the filter first, with the alcohol/oxygenated fuels being swapped in and out seasonally we end up with clogged filters every spring and fall when the change the formulation.

fwiw

i don't know what the minimum fuel pressure should be for your application, in order for it to inject, but i suspect it is north of 40psi, but maybe not,,, in any case i would change the filter and see what that does,

still no start check the pressure and compare it against the minimum standard, if it is too low...

find the return line from the engine to the frame, and pinch it off and see if the pressure spikes higher, if it does then you might have a fuel pressure regulator problem

if on the other hand it does not come up well over minimum, the pump is tired.

bob g

viper · Mar 4, 2010

RAS said:
Ok, after re-checking, it looks like the fuel pressure is low; hardly any comes out of the pressure test valve when the key is on. I guess I'll replace the fuel pump first. Is there access for that through the trunk (trunk is packed full right now.)?

RAS

Do I win anything?? lol

I agree to check the filters before replacing the pump. When they sit, all sorts of crap can happen. Also make sure your pump is getting power. Had one with a bad wire in the frame rail.

tailstock · Mar 4, 2010

Had a 350 once and thought it was a fuel pump problem but turned out to be the fuel pump relay on the firewall. Just a thought and a whole lot cheaper and easier than an in tank fuel pump. Also found that the inline fuel filter should be changed about once a year. If it is restricted it will ruin the fuel pump. A lot of pump problems can be traced back to bad filters.

JunkyardJ · Mar 4, 2010

Well, fuel pressure won't happen until the engine runs.

I'm pretty sure on that car, the fuel pump will kick on for a bit when you first switch on the key, then shut off. You should be able to hear it, or the fuel pump relay clicking under the hood. This is just enough to prime it, the pressure SHOULD stay up to whatever it's supposed to be, but if something leaks, it will bleed down. Usually something gets stuck in the check valve in the fuel pump. Sometimes an injector gets stuck open. The car should start anyways, there's just a trick to it. Turn the ignition on, and listen for the pump to prime up. You should hear the pump bog down, might take a few tries. Then turn it off for a split second, and immediately try cranking it over. If it fires up, something probably got stuck in the check valve. Wouldn't hurt to change the fuel filter either, but beware, it sometimes takes a while to get all the air out. I usually take the core out of the schrader valve (tire valve), and run a piece of fuel line into a gas can. Then bypass the fuel pump relay until I pump a half a gallon or so of fuel.

I find that an LED with the proper resistor makes a good noid light. If you hook it up backwards nothing bad happens, so it doesn't hurt to try it both ways.

If you get a spark, more than likely the crank sensor is good. Not sure if the cam sensor controls the injectors or not, but it might. Finding out what codes the computer is spitting out would be a good start. Good Luck! :cheers:

VPT · Mar 5, 2010

You can see injector triggers with a test light while cranking. On most cars there should be power to all the injectors when the key is turned on, the ecu uses a ground to trigger the injectors.

Like mentioned though check for fuel pressure first. Chevys are very well known to dislike fuel pumps. I have replaced my grandfathers fuel pump in his 98 buick with only 56K miles on the clock. I replaced it with a honda fuel pump and it has been fine ever since. I have had to replace my brothers chevy trucks fuel pump, my Dads chevy truck fuel pump, many friends chevy truck fuel pumps, it is a known problem that chevy won't recall.

Dave Converse · Mar 5, 2010

GM fuel pumps weren't as fragile in 88 as the later ones mentioned. Good advice on the noid light to check injector pulse. Forget the coil packs (and all ignition parts) because you already said the engine runs when squirted with starter fluid. Be sure you have 12VDC at the fuel pump before condemning it............if necessary, use a jumper straight from the battery to hear the pump run temporarily. If no voltage upstream of the pump, check relay.

As a shop owner back when that Cutlass was numerous, I recall having to replace a lot of ECU 'proms' as they failed often. The 'prom' is the program and is just an updated chip that plugs into the ECU's board. If everything else checks out but you still have no pulse at the injectors, the prom is possibly your culprit.

The best diagnostic technique is to check things in sequence, either back from the known malfunction, or forward from the last spot things check out OK......................you're looking for the spot between where the "garden hose has water pressure and where it does not." There, you will locate the problem. The thing you take for granted usually will humble you.

OT Another car problem-no power to injectors

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