Over Fuelling

So,

As the name suggests, our Beaner is drinking more than the uk in a post lockdown pub.

Supposed to be getting somewhere around 190-200 to a tank but we filled it up, drove to Brighton and we were on fumes after just over 100.. which is not good. It’s had new oil, filter, air filter and plugs so I don’t want to keep driving it around giving it more of a chance to coke everything up again.

Before I go any further I just want to say that I have read the (extremely informative) faulty sensors sticky and I’ve been trying to work my way through it to check all my sensors.

Intake temp sensor
Seems to be working fine, resistance behaves as it should after a good warm blow (oi oi).

Coolant temperature sensor
Not getting any reading from the dash gauge side of the sensor yet the gauge still works, is this suspicious or a ‘if it ain’t broke’ scenario? Would this affect the sensor as a whole?
Getting a resistance reading of around 4.8 when stone cold yesterday at about 6 Celsius so this seems to check out. It’s not been driven anywhere since but we’re getting a Christmas tree tonight so I’ll have another look when we get back for a comparable reading. I’m assuming if the temp sensor is broken there would be no reading of the cold reading would be incorrect?

Map sensor
Here’s where things get slightly confusing for me. On the sticky it says in order to test the sensor you ‘stab red probe into the red and white wire’ and black probe to ground.
Our van doesn’t have a red and white wire, on the plug it is a green, a brown/white and a solid red. I tested the red as this seemed the only one with a voltage and it read about 3.8v with ignition on. When I tried to test the same pins with the engine running (noticeably poorly) it basically cut out and the readings were all over the place.

Also, stupid sanity check question! Am I supposed to test the wire on the plug or the prong on the sensor? Because surely testing the plug wire tells me nothing about the health of the sensor itself?

TPS
On the sticky it says that ‘the red and yellow wire is the one that needs testing’ yet our van doesn’t have one!
We have a green, purple and pink wires. So I need a nudge in the right direction for this one.

Is there anything else I should immediately check if fuel consumption is pushing 200%? I’m ruling out the stupid cherry bomb exhaust as yes it would be more thirsty but not twice as much surely?

Brakes aren’t binding, clutch isn’t slipping and throttle is adjusted correctly (in case it’s important)

Getting so close to the mechanical finish line with this thing now, I just need some help to sort this last issue and we can get on with the conversion!

Thanks in advance Hijet Gods.

Beaner

We topped it off before we left and put about £30 in when got back so I’m quite sure it was pushing the limit. It was nowhere near half full so it’s definitely drinking. The smell of petrol is also quite evident at traffic lights so that leads me to believe it’s running rich too.

Fuel tank leaking as that seems a common issue?

Fuel tank has only just been out to solve a sender issue and has been triple checked for leaks so it’s 100% not that.
I’m quite convinced that it’s something to do with fuel regulation from a sensor or something.

On something as simple as a Hijet EFi system there really are only a couple of things that determine fuelling control.

Fuel pressure regulator and vacuum feed on the end of the fuel rail - this is the largest factor. Vacuum decreases rail pressure, e.g. idling or pedal lift off requires the lowest fuel. WOT (wide open throttle) requires the highest fuel. If the vacuum is not plumbed up right, of the diagram in the FPR is sticking over fuelling will occur.

MAP sensor, this reads the manifold vacuum level, and from this the ECU alters injector pulse width, and ignition timing. The MAP sensor is nothing more than a variable resistor attached to a diaphragm. It has a 5v feed, a ground, and a signal wire. The signal will sit somewhere around 2.5v at atmosphere, and reduce down to 1v at a full vacuum. They either work or they don't.

Lambda sensor, in the exhaust, this measures oxygen quantity in the exhaust gases. If there is oxygen present then it is running lean, if there is no oxygen at all then it is rich. The sensor makes voltage all on its own just like a battery. They make 1v if rich (no oxygen) and 0v if totally lean (lots of oxygen).

Engine/coolant Temperature sensor - this slightly bends the fuelling to make it richer with a cold engine.

Intake air temp sensor (in the induction pipe), this slightly bends the fuelling to correct for air temp, because if the air is cooler then there is more oxygen available as the air is more dense when cold.

I would always keep this sort of trouble shooting as simple as possible, making sure the vacuum pipes are function correctly and plumbed in correctly is a massive starting point. And making sure the Fuel Pressure Regulator is functioning correctly is worth while. In the distant past I found maybe 3 or 4 with a stuck FPR, mostly I think because the tanks rust inside. I always just check the ignition timing with a timing light, because the cam sensor on the back end of the head has adjustment and is often refitted incorrectly, it is also common to see the timing belt fitting 1 tooth wrong too.

When they are running properly, they go "like a rocket" (for a hijet), and will go off the end of the speedo on a flat road.

Ok excellent.

Simple troubleshooting is what I was hoping to hear! I’d much rather strip and clean something than buy a new part any day.

Does anyone have any visual references of how the vacuum lines are supposed to be plumbed as a reference? Our manual is the worst photocopy you’ve ever seen so all the images and diagrams might as well be hieroglyphs.

I’ll check out the FPR today, that sounds promising so hopefully it’s something to do with that. We are getting voltage reading where we need to be so the sensor issue is looking less likely. As you say, the MAP sensor either works or it doesn’t and there is a notable difference without it so I can rule that out.

Thanks so far, will report back once I stink of petrol and I’ve got frostbite!

Hi guys,

Pulled the FPR this morning and checked all the vacuum lines. Everything seems to be going where it should be and there was no evidence of fuel where it shouldn’t be so I don’t think the FPR has a tear in the diaphragm.

I also let the van run for a while and double checked the tank again looking closely at all the fuel line connections and every hole in the thing and it seems to be buttoned up tight so it’s not that.

My question is how do I test the FPR? Nothing inside wants to move either way when I blow through it but I know fuel pressure is meant to be probably higher than I can blow so it might just be me being an idiot.

What’s an effective way to free up the mechanism? Can I give it a toot with an air gun or do I risk damaging something? Very hesitant to start poking metal things into holes given there are rubber bits in it. Or if it’s replacement time, does anyone have a lead on where I can find one. Parts for this van are annoyingly hard to find.

Thanks
Beaner

You have checked air cleaner I expect
I have a 1.3 16V manual in PDF pm me if you want it with email
Or go to search Manuals