Hi all. Ive got a 1989 Jap spec infiniti q45. It has fuel pressure, spark and an injector signal and still wont run. Any ideas? Cheers Im located in Australia

mac, got spark- cause you removed at least one plug ? How the plugs look mate? You have AN injector "signal",if that means you read voltage/logic probe on one only Injector ? I f 'n the rest are getting a signal is something to verify and if connectors are removed(f/inj.) you may now test for the typical 12-14 Ohms reading on them'. Next order of business is , where was f-pressure tapped from ? ,in other words - you guaranteeing gas IS in fact IN the rails UNDER FULL/normal pressure .Let's see - an engine needs : pressured fuel , spark @ the plugs! , and COMPRESSION ! - Do compression test If 'n you've got all the plugs out because you decided to fully inspect them . G 2/27/2018

Plugs looked ok. The car has only done 40000 ks. Ive ordered new plugs anyway. I checked the injector pulse with a noide light, yes i only checked one injector.. The fuel pressure was checked between the fuel filter and fuel rail. Withe plugs out, you can smell fuel when winding over the engine.The car was running great, went to the spray shop, came back like this.

mac , "Spray shop" = bodywork = PAINT Then I spose I left out one thing ? Airflow ? Did they CHUCK a rag over an intake , or even If 'n a mate playin'a JOKE stuffed that rag for no O2 ? G

Only painted the top surfaces. They said it was fine, then started to run ruff and stopped. It wouldnt restart. Thats where im at

ill throw a set of new pugs at it and see what happens. Be nice if it is that simple.

Hello and welcome to the forum!

New plugs are never a bad idea, especially if you have already paid for them.

You have fuel and spark, how about air or the metering of it?
Spray shop you say? I hope your air filter is in good shape, but is it possible paint was inhaled into the air tube and would be coating the MAF (mass air flow) sensor if the filter hasn't gotten clogged by now?
At minimum visually inspect the components and maybe pull the MAF sensor and clean it with the proper chemical.

Obvious question here - is the check engine light on and have you tried to scan for codes regardless?

mac , I think EdBwoy has brought up the possible effects of "overspray" blockage -that would pretty much covercompletely the AIRFLOW question .Now I go back to your quote " THEY said it was fine , then started to run rough and stopped " Me thinks , it's an '89 ? what was the Timing Belt like (chain??) ? The THEY ,I hate to suggest might have BEAT your motor Tooth slippage - one "jump" ya know- would act just like that ??

"It's just a jump to the left ......" Hiyoooo !

My 1995 Q45 has been down since March 2017. She was running with NO problems. I went to help my Son with his Ford Bronco, came home, and turned her off. Next day NO START. Just cranked, no ignition. Full tank of gas. My Q45 has had a history of fuel pumps going bad, so it was my first suspect. I removed all the trunk pieces, and spare tire, to get to the fuel pump. A few days ago I disconnected the antenna motor so I could hear the fuel pump cycle. The fuel pump is turning on and cycling, then turning off. I also smelled fuel from the engine. No Ignition. My next logical step...would be to check the pressure. QUESTION: What pressure am I looking for. Also, do I just disconnect the hose coming out of the fuel filter, and place the pressure gauge inline? Can these be rented at the local auto parts store. Thank you for any information!!

Sounds to me like one or both of you may have a failed fuel pump control unit (FPCU). Simple test is to bypass the unit with a jumper cable. The FPCU is accessed through the trunk and is mounted underneath the rear parcel deck. You can see the FPCU in the background of the pic. Run a jumper cable from the pin shown on the connector to ground. If the engine starts the FPCU has failed.

to NICO!!

I'm not sure what the weather is like in your part of the world, but it's possible that the engine is flooded. In cold temperatures, the ECU sends a particularly heavy hit of fuel to the injectors before a cold start. Think of a reverse old-school choke... but instead of enriching the fuel mixture by cutting air, they're doing it with more fuel. If the car is started in cold weather, moved a little, then shut off - all of that extra fuel can wash the oil off of the cylinder rings, causing low or no compression. The ECU has a feature to bypass the enrichment at startup that involves holding the gas pedal to the floor during starting. Typically you'd floor it, turn the key, and don't stop until it either starts or the battery needs to be recharged. We typically see these issues at about 40F (4C).

As others have mentioned, I'd check fuel pressure... a super fast bleed down after shutting the car off could indicate that an injector is leaking in to the engine, and cause a similar issue.

its 40 c here. I think thats 100 in f.Thanks for the info about the fpcu. Waiting for my plugs to show up. If it still wont start ill give it a try